There have been a lot of prior threads about this. Consensus is coming around to saying "no". I'm an old timer and come from the days of Leupold MK IV seperate rings and two piece bases. In those days, you lapped and it was generally necessary (because of sitting on R700 actions).
Nowdays, with modern CNC machining repeatability and one piece bases, it really doesn't seem to be necessary. I purchased a QD one piece mount from a very reputable manufacturer a couple of years ago. Popular opinion was that no, I didn't need to lap. I thought, OK, all the arguements against lapping seem credible, but I'm going to go ahead and lap, just to see what the fitment really is. After a short time lapping, I looked at the fitment and concluded that no, it really hadn't been necessary. But, I did it to satisfy my curiousity. I would be hard pressed to think about lapping the rings in a one piece mount. Individual rings and bases are a different matter though. What many people seem to lose track of is the possibility of mis-alingment (of two piece bases/rings) because of the action. Within reason, the only way to compensate for the mis-alignment is by lapping. I have standardized on Spuhr 4006 one piece mounts, have never lapped any of them and never will. The repeatability and consistency of modern CNC machining has gotten to the point where I just don't think it's necessary anymore (but, I had to prove it to myself)