it would be nice to dictate whenever something is 'active' as it seems using 'AAP' (animated animator parameters) does not trigger it.

for making a Prop-Slot system look nice and not be a mess, you would need a system to detect whenever a certain 'Slot' is being used, But, once its 'taken out' of that slot, then disable the parameter seamlessly.

You cannot do this with AAP as AAP requires floats, and not bools, and cannot be used in logic it seems, as they set the Value, but not the Expression value, (as tested with AV3Emulator, and ingame.)

Other more complex systems could use "On Exit" aswell, as it would only be ran when the state gets transitioned out.

(Parameter Driver Behaviours could even be stacked into one state, one to Enter, one to leave, unless 'Type' could be changed into OnExit instead, or the entire system Rewritten to be like AnimatorPlayAudio.)

i've attached a little simple design of where On Exit could be easily placed.