When I worked Bull, I learned that no matter how fast the trains are going, the first 10 dispatches of a day are never, ever trimmed to minimize the likelihood of valleying before the lubrication loosens up in the mornings.
If you ride immediately after a reset, you also get a trim-free ride. (the ride almost never goes down, so this is rare.)
The ride is indeed awesome when the trims don't hit.
Part of why it is so hard to get an untrimmed ride comes from the fact they do Lead Ridesas part of the morning checklist. When three trains are on, for the Lead to ride all three trains, it takes 11 dispatches to complete the checklist. The guests can only get the last untrimmed rides of the morning when two trains are in use.
There are three trims: the first is at the pre-drop dip on the lift hill. This one is always keyed off. The second is on the way back up after the first high turn. This one virtually always hits, unless it is one of those circumstances I mentioned earlier. The third one is usually about 50/50. The computer activates the trims based on a combination of the previous train's lap time and the time the current train completes the block before the trim in question.
TLDR: The ride is trimmed into mediocrity.