I guess I got into Mosaic at the right time for me, as the sets I've bought duplicate little if any of what I have. I picked up the Lee Morgan when I was in my "gotta have all the Mogie I can get" kick, and hadn't I picked up anything before Sidewinder yet. Then I got the Anita, which had just the period I wanted from her, all of it, and I only had one CD from that period. In fact, I don't think I've ever bought a Mosiac that really duplicated anything I had other than that. As strange as this sounds to my wife, with just 500 or so jazz CDs, I just don't have that much...
Now, there are some Mosaics I'll never own. The Blakey for example. What would be the point? I've already got the individual CDs. Same with Tina Brooks. The tough ones are ones like the Byrd/Adams, where I have two of the CDs covered, but not the others. I don't know. We'll see when "last chance" time comes, I guess.