I have to admit that I probably never noticed regularity of her sleep.
When is it shown?
I'm not sure if she's really planning around new activities. It may be just my projection, but I thought that she's just creating solid excuses not get involved in activities, that can potentially be annoying, or uncomfortable - which is something I can pretty much identify with. Those two interpretations may seem very similiar, but it's a part of the nature of the show, that most of those activities are forced upon her and that's when the INTP's stubbornness kicks in and this is just her way to avoid pointless confrontation with the authority in question.
It's just my view though, since I can see how it can be interpreted both ways. After all, she's a fictional high schooler, that could've been possibly created to appeal to INTs.
I like the episode you mentioned, and the quoted dialog is obviously an author's way to express their differences. I'm not sure, if the intention was exactly P vs. J, but it is really pointing in that direction. The thing is, that I always assumed, that those main characters are more based on some real live experiences, than that they are supposed to (creatively) represent some stereotypes (unlike most of the other people on the show). For example I'm a strong P, but I'm addicted to wearing a watch, even if it's just for having an easy access to knowing how much time I can still waste at the moment.