Mr. Teapot
First Post
Simply standing still to gain CA has a notable opportunity cost in and of itself, because it means that you aren't using a different trick to do more damage or damage an additional foe or go into hiding or knock prone.
Sure, there's some limit, but it's been utterly trivial in my experience with it so far; there's always a lone opponent somewhere. (If there isn't, then the enemies are bunching up for the wizard!)
Note that a Slayer can get very nearly the same damage every time with no conditions, no constrained actions, higher AC, hit points and surges. You go with a Thief for the skills or because you like the style of play, not for the extra damage relative to the Slayer.