I usually establish a punch intensity that I am comfortable with ahead of time with the partner and go from there, depending on my mood and energy levels its usually 10%-70%. I actually am much less urgent once im set-up somewhere (RG, guard, mount) because the other person will be out of energy pretty quickly. About 3 minutes tops usually. I do believe in actually making contact though, some people like to throw off-center punches, I think this screws up the realistic punch angles.
Does anyone find that too much non-punching sparring makes different reflexes? I recently was sparring with someone with punches and they established a decent base, I found myself going for an open guard sweep instead of focusing on the upcoming GNP. Lesson learned but I was a little alarmed.