I don't think I ever had the slightest interest in writing in SPN or HP, so it was really easy for me to just graze, but I'm a sort of nervous/obsessive completist in fandoms that I have fic ideas for. (see also: my inability to let go of most plot bunnies or any WIP).

And there's also a helping of "if I'm going to try to engage, I want to encourage the other people who are trying" which is. Well, I'm not great at that to begin with so it's laughably impossible in large fandoms with juggernaut ships.