That's an answer I don't have. I would just focus on grabbing what has the fewest copies for the snap-shot in time when I am downloading the files. Other archivers will grab what needs more copies at the time they download, just as you and I are basing our downloads of what has the fewest existing copies weighed against what others have seeded before us.
Its a churn of archivers "rotating" the content we each choose to preserve(almost entirely without regard for WHAT the specific content is).
If enough people were too active about deleting what they've downloaded that has "enough" copies and replacing it with content that doesn't ... okay, that's unlikely, but we still need more seeders in general, and those of us who keep on seeding that which we've already downloaded make the decision of what needs more copies seeded in the future easier to make for new archivists and/or those who have invested in more capacity.
The registry and minors being added to it is the topic of the OP and every comment that follows. Your supposed ignorance of the concept was exhausted as an excuse already.