In The Artifact game book and in the last post I espouse using time limits of 30 seconds on players declaring and rolling for actions. I’m going to suggest a modification of that here.
It occurs to me that it allows the same level of planning to all players and quicker thinking player can still get all they want to do in even if their character is slow (has a low REF).
Because of that I suggest giving the player a number of seconds equal to their REF attribute to declare and roll. That’s a bit harsh for characters that have a 10 for Ref but I’d go with it. It also takes into account that a player with a 66 for REF has 3 actions to declare and roll for while a character with a 30 only has one and doesn’t need as much time.