I think this is a question for each teacher to think through for him/herself. I know there are some teachers--or perhaps even some administrators--who want that "accountability" piece.
I feel like I think you do :). The fact that I'm having each student check in before they go to a round and tell me the strategy they are working on, and that we come together to share a bit after each round, that I have a pretty good handle on what they are doing.
Also, I kinda feel like we are working so hard to build independence in our students, that adding the requirement of "exit slips" or whatever one calls them, takes away from our belief that kids can do this.
I know there are kids who need to be reminded to keep on task, but that's another lesson--work the whole time you're there!!
Again, this is my opinion, and I'm sure others have great ideas to share with us.