I didn't know this was a "law", but i've been triangulating on this same feeling for a long time now. I would say it's 1%-10% of anything is actually good. You can basically apply this to almost any category, but for most things it doesn't really matter. I would guess while no two people would agree if asked to pick their top 5% of any one thing, if you tallied up all the votes and had enough participation, you could probably put together a list that would generally include the best of whatever that category is.