I don't really pay attention to it, but I definitely notice if my boyfriend and I haven't had sex in a few days. I actually had hurt my back recently so we had to take a break while I healed. It was almost two weeks and I was going insane!
I don't deliberately keep track, but I do remember anyway. I can fairly easily recall almost all the times (if not ALL the times) we've had sex since at least the beginning of the year, and what we did. Now that I think about, that's kinda scary!