Should an actor decide their own blocking in this case?

[rsbush]

Yeah, so maybe the directing should be doing more in blocking, but if they are not, then should I as an actor do my own, in order to keep up with the other actors' blocking?

You should have discussed it with the director. If you felt that questioning the director would be disruptive to production, and believe your cast mates were disregarding their blocking rather than incapable of following it, you should have spoken to them. If you were completely unsure, you should have allowed yourself to get carried away and "lost" from your blocking. If noted by the director, you should have taken the note. And you would now have your answer for the specific situation you were in.

You solve the specific acting problem that you experienced, by addressing it as it is becoming a problem, in as non disruptive a way as possible. It's the only way to get the answer you need for that specific production. Every production is unique and requires an adjustment toward that uniqueness.