Another quick comment. You mention that you don't really put a lot of effort into predicting Sunday ownership % by looking at Thursday lineups. Neither do I. I know some very successful DFS players who put a big emphasis on ownership percentage, but I could never bring myself to care about it all that much because, while I acknowledge that it's useful in principle, I think its usefulness is significantly overestimated in contests with nine roster spots. (It would make a much bigger difference with much smaller rosters.)
Anyway, it got me thinking about another analogy to poker. In poker, there's exploitive play and game-theory-optimal play. With exploitive play, you're trying to identify and take advantage of specific mistakes your opponents are making, and you'll depart from standard play yourself in order to do so. With game-theory-optimal play, you're trying to avoid making mistakes yourself -- to avoid being exploited by others -- and in the process you'll automatically benefit from others' mistakes even without specifically identifying them. It's helpful to have both styles of play in your arsenal, but the general oversimplification is that you'll maximize your win-rate against bad opponents by playing exploitively, and you'll do better against other experts by using a game-theory-optimal strategy.
It occurs to me that a similar distinction exists in GPP strategy. In GPPs, it helps to own under-owned players and to fade over-owned players. There are two ways to do this. (1) You could try to determine how frequently a player should be owned, then try to anticipate how often he will actually be owned, and then go out of your way to roster players from the first category and avoid players from the second category. (2) Or you could try to determine how frequently a player should be owned, and then try to own him with that optimal frequency. In so doing, you will automatically have a higher ownership percentage of under-owned players and a lower ownership of over-owned players than the field -- all without ever paying attention to anticipated ownership percentages at all.
I'm partial to the second method. It might leave some money on the table when there are genuine ownership anomalies from time to time. (For example, Tom Brady was apparently 25% owned in the Thursday contests this week, which is probably too high. If I think he should be owned 9% on Sunday, I might actually be better off owning him 0%-4% rather than 9% in order to exacerbate my fade of an over-owned player.) But for the most part, the big crowds aren't usually off by that much all that often. So my time might be better spent working on my own evaluation of his optimal ownership frequency instead of worrying about how often other people are likely to own him.