After a while, a lot of special treats become less frequent because sex in general slows down at least a tad from the "can't see air between them" to the "been married and are tired and old" periods. Unless you are a super athlete or something your drive drops with age, anyhow. In my personal experience, the decline in blowjobs is also directly proportional to how much you reduce your muff diving frequency. Basically, Hoss and BigW are spot on. But anything that you can do to jumble the routine up will help both your relationship and your sex life. Routine is the enemy of intimacy.