Sometimes I strop while shaving, but not often. Sometimes I'll strop before my ATG pass; sometimes I'll strop before more difficult areas (like the chin, or around the upper lip). I do find that it helps a bit, especially if I'm doing three passes, but I've never found it to be necessary.

I also don't particularly enjoy stropping, and I don't usually wait for lather to soak into my face/beard (I shave after I shower), so there is no real incentive for me to strop while shaving.