In an animation statemachine you can test the anim curve VS a hard value to enter/exit states.
In montages, you just play the next one at the right time - pulled from the anim curve.
The angle able is what you use to test the current state.
You can also use it to start an animation at a specific spot.
If the animation is set up for it, but thats far more complex.
If you built in c++ I may share some code that pulls the starting time by finding the curve values and returning an array. If you need to start at a specific frame thats pretty much the only right way to do it. Unfortunately, its a bit processing heavy.
It could be better to just copy/paste a curve into a curve asset and query the curve asset for the specific animations that require this behaviour.
Basically take the animation part out of the query portion…