> Could the user have trouble perceiving the change in state that just occurred? If so, then use an animation to help them visualize what happened

I think this is the only justified use of animation in UI, however I wasn't satisfied with the dilemma of increasing perceived transition while increasing perceived UI latency.

I found it's possible to get the best of both for event triggered state changes i.e clicking on stuff, by sticking to ease-out based transitions, where the start of the transition is instant and the end decelerates.

This makes it feel just as snappy as no animation, while still helping to communicate a transition, because we are more sensitive to the latency of the start of the transition when it's an event - since we are anticipating a reaction, which is satisfied as soon as it starts to react.