Hey Steve, I'm sure you will agree one of the most interesting spots is the Ks4s2dAh hand at 18:00. I've been exploring some sims along the same lines and have come to the conclusion that the condition to use the block size on the A turn is when OOP uses a large size. The frequency of betting is increased when we hit the A more, and our opponent does not. So as well as when we use the large size (and villain folds naked A-high), it also happens on two tone boards since we are likely to raise nut flush draws and the nut flush blocker, and wheel boards since we raise Ax draws.

Due to these conditions, we hit weak top pairs therefore we have a middling portion of the range that is driving the bet size.

Super rare spot and probably not a great use of time but sometimes you just gotta find the answers!