In short, yes. Your method is crude, but works in theory in crude situations where there's a decent amount of space between vehicles.
A maximum number of trains, no. The ride could have any number of trains, and your linear suggestion would work
if the ride had a block system which was suitably spaced out. The thing is, rides with a large number of vehicles don't have such nice spacing between blocks.
So yes, it depends much more on the ride and how it's composed, how the blocks are laid out, etc. As Undead Creature says, this is why the block system is important, arguably more important, than cycle time.
As you may well be aware, the maximum number of vehicles you can have on a coaster is one less than the number of block sections. That's because a vehicle cannot enter a new block section until the vehicle in front has cleared it.
Look at something like Colossus at Thorpe. That has 3 block sections: Station, the Lift Hill, and the Brakes at the end of the ride. So the maximum number of trains it can have is 2.
Smiler has more: Station, Brakes before Lift Hill 1, Lift Hill 1, Brakes before Lift Hill 2, Lift Hill 2 and Brake run at end of the ride. That's 6, so maximum number of cars would be 5.
I think really it's best understood with an example with real numbers. Let's look at Lech in closer detail.
- Lech seats 20 people per train. To hit 500pph, you would need to send 25 (full) trains per hour. That's a dispatch every 2mins 24sec.
-One 1 train, it seems to take
1min 43sec for a train to run from station to station (based off
this video).
-This means that in the theoretical throughput, Vekoma allow
41secs for a dispatch.
Lech has 4 block sections:
Station,
Lift Hill,
End Brakes 1 (immediately after the ride) and
End Brakes 2 (after End Brakes 1, just before the Station) .
On 2 trains (call them Train 1 and Train 2), you have the following situation: You send Train 1, and Train 2 rolls into the station shortly after. You can send Train 2 at any point after Train 1 has 'cleared' the Lift Hill, in theory. However, you ideally want to send it so that by the time Train 2 reaches the top of the Lift Hill, Train 1 has cleared End Brakes 1. In other words, Train 1 needs to be in End Brakes 2.
Of course, you can dispatch Train 2 at any point. However, this either means the lift hill goes slower than the optimal speed, or Train 2 stops on the Lift Hill. In either case, an earlier dispatch could mean you have the contradictory-sounding situation that the train ultimately ends up leaving the Lift Hill later than if you dispatched it at the 'right' time.
On 3 trains (Train 1, Train 2 and Train 3), it becomes trickier. You start off with Train 1 in Station, Train 2 in End Brakes 2 and Train 3 in End Brakes 1. Train 1 is dispatched and hits the lift hill, allowing Train 2 to roll into the station, which means Train 1 can go into End Brakes 2.
Train 1 then leaves the lift hill and goes about the ride. You only want to dispatch Train 2, however, when you know it can clear the Lift Hill. For that to happen, you need End Brakes 2 to be available for it. That can only happen when Train 1 is in End Brakes 1, which in turn can only happen when Train 3 is in the station. But that can only happen when Train 2 is dispatched.
This means there's only a small window of time when it is optimal to dispatch Train 2.
And this whole process repeats.
So anyways, let's look at some numbers again, again using
this video:
-Time taken to go from Station dispatch to bottom of lift hill: 14secs
-Time taken to go from bottom of Lift Hill to top of Lift Hill: 22secs
-Time taken to go from top of Lift Hill to End Brakes 1: 47secs
-Time taken to go from End Brakes 1 to End Brakes 2: 10secs
-Time taken to go from End Brakes 2 to Station: 10 secs
(The brake times will be a few second longer with multiple trains as they will have to include stopping the train and getting the train moving between the brake sections, whereas the video, with 1 train only, they just fly through. This is an important caveat to the multi-train case!!).
So 1 train is easy, in theory. Train takes 1min 43secs to go round the course, you take 41secs to unload/loads train and do safety checks. Boom, 25 trains sent an hour, 500pph.
Two trains again is fairly straightforward.
-0secs: Dispatch Train 1 from Station. Train 2 sat on End Brakes 2.
-14secs: Train 1 at bottom of Lift Hill, Train 2 moves forward.
-24secs: Train 2 in station
-36secs: Train 1 at top of Lift Hill and goes through ride.
-1min 5secs: Train 2 in station for 41secs, can now be dispatched (as Lift Hill is clear).
-1min 23secs: Train 1 at End Brakes 1.
-1min 33secs: Train 1 at End Brakes 2. This is the earliest moment that Train 2 can leave the Lift Hill.
-1min 43secs: Train 1 returns to Station.
-1min 46secs: Train 2 at top of Lift Hill, and as End Brakes 2 is clear, moves on.
Rinse and repeat.
In other words, the addition of the second train doesn't slow down the allowed time for dispatching a train, because all relevant blocks are cleared when needed.
So each train is sent 25 times an hour. 1000pph.
Now let's look at 3 trains. I'll go for a bit longer to show what is happening:
-0sec. Dispatch Train 1 from Station, Train 2 sat on End Brakes 2. Train 3 sat on End Brakes 1.
-14secs. Train 1 at bottom of Lift Hill, Train 2 moves forward. Train 3 still on End Brakes 1.
-24secs: Train 2 in Station. Train 3 can move forward.
-34secs. Train 3 is in End Brakes 1. Train 1 is clear to leave the Lift Hill and go through the ride when possible.
-36secs: Train 1 at top of Lift Hill, and leaves as End Brakes 1 is clear..
-1min 5secs: Train 2 in Station for 41secs, can now be dispatched (as Lift Hill is clear).
-1min 19secs: Train 2 at bottom of Lift Hill, Train 3 moves forward.
-1min 23secs: Train 1 at End Brakes 1.
-1min 29secs: Train 3 in Station. This is the earliest Train 1 is allowed to move from End Brakes 1 to End Brakes 2. As it is in End Brakes 1, it moves immediately.
-1min 39secs: Train 1 at End Brakes 2. This is the earliest moment that Train 2 can leave the Lift Hill.
-1min 41secs: Train 2 at top of Lift Hill, and as End Brakes 2 is clear, moves on.
-2min 10secs: Train 3 in Station for 41secs, can now be dispatched (as Lift Hill is clear).
-2min 24secs: Train 3 at bottom of Lift Hill, Train 1 can move forward.
-2min 28secs. Train 2 at End Brakes 1.
-2min 34secs: Train 1 in a Station. This is the earliest Train 2 is allowed to move from End Brakes 1 to End Brakes 2. As it is in End Brakes 1, it moves immediately.
-2min 44secs: Train 2 at End Brakes 2. This is the earliest moment that Train 3 can leave the Lift Hill.
-2min 46secs: Train 3 at top of Lift Hill, and as End Brakes 2 is clear, moves on.
-3min 15secs: Train 1 in Station for 41secs, can now be dispatched (as Lift Hill is clear).
-3min 29secs: Train 1 at bottom of Lift Hill, Train 2 moves forward.
-3min 33secs: Train 3 hits End Brakes 2.
-3min 39secs: Train 2 is in Station. This is the earliest Train 3 is allowed to move from End Brakes 1 to End Brakes 2. As it is in End Brakes 1, it moves immediately.
-3min 49secs: Train 3 at End Brakes 2. This is the earliest moment Train 1 can leave the Lift Hill.
-3min 51secs: Train 1 at top of Lift Hill, and as End Brakes 2 is clear, moves on.
The sections in bold are the most important things. If everything runs like this, you have a period of 2 seconds of wiggle room. BUT, they don't, because this doesn't take into account the time it takes when a train stops and restarts. Say you then have to add an extra 5 seconds to move between End Brakes 1 and End Brakes 2, and an extra 5 second between End Brakes 2 and the Station, that's an extra 10 seconds which needs to be accounted for.
That can be achieved by, say, slowing the lift hill speed down, or giving more time in the Station for a dispatch. But in any case, it slows the time in which you can dispatch a train in theory. All that time means that instead of being able to send each train 25 times in an hour (as you can, in theory, with 1 or 2 trains), you can only send each train 20 times an hour, in theory.
So that means achieving 1500pph (the 500pph achieved on 1 train multiplied by 3) becomes an impossibility, and it brings the theoretical throughput to 1200pph.
Obviously this all goes down the drain when you add in guests, checking bars, etc. I'd imagine that with the set up, 3 trains literally would not get a meaningful higher throughput than 2 trains, except in exceptional circumstances.
In other words, Lech is not a ride that's really designed to run 3 trains efficiently or effectively.
---
Okay, that's a lot of waffle. Hopefully it makes sense and the maths adds up. Though it very well might not. But in any case, that should give an insight into why theoretical throughputs work the way they do.
The important thing to note is that rides with a sense of uniform spacing between blocks have a better chance at being closer to the theoretical throughputs in practice (as long as they have well-designed stations, efficient staff, etc). Rides with LOTS of vehicles have added complications if their block sections are awkwardly spaced. Something like Smiler, for example, never did much better on 5 trains compared to 4 trains because the block system, along with the operations, meant it simply never worked. Saw is similar: the different in practice between 7 cars and 8 cars in minimal.
Anyway, to give clear, short answers to your questions:
Yes, if a coaster with a lot more cars has an awkward block set up. But as a simple, crude method, it's not bad for get ball park figures.
Pretty much, yes.
(Saw is also a difficult case to look at given the dual dispatch, etc. My advice would be to try not to understand the throughput of that!)
To reiterate (since I waffled): It's more accurate in the first situation you suggest. It becomes less accurate in the latter, but still okay in the grand scheme of things.
The more important thing is the design of the ride and its block system, and how well it can handle its given number of trains. The number of trains is less important.