There's no set time. Sometimes, I've watched the same one a few times in a short period of time, because I've been discussing it in threads here, but ordinarily, I take a break from one whole show for large stretches of time, like many months, but then I'll get the hankering & over the course of some weeks, watch a bunch & my favorites usually find there way into that run.
I'll rewatch TNG, TOS, & the movies, & I'll mostly frequent them one group at a time, until I've exhausted my craving for it, at which point I'll take a break for weeks/months & then when I get the hankering again, I move to another group, & so on. The good thing about Netflix is that while I don't care to rewatch DS9 in large blocks like the others, because of how arced it was, there are a few ones in there that I throw into the mix now too, & I'm trying to find ones in Voyager & Enterprise to do that with too
That's me. When I want to have a binge type period of weeks, I like episodic stuff, because it's lighter fare, & by finding episodes from the whole of the franchise, I can make a wider variety of a viewing experience than just binging on one show. It's changing my perspective on the franchise, because I'm growing to think of it all as one collection, even though I'm still not much of a fan of some the shows. I do accept them more & more... which is good, because I think it'll make me more tolerant of the modern things that are being produced now, even though they are so different & not really what I value in Star Trek
Avoid learning it inside out??
I know, right. I've seen TNG so much, it's impossible to not know them inside out. Pretty much TOS is getting that way now too, since Netflix. It was less memorized to me before that, as I've never owned any copies of it, & only knew it from televising, which was still surprisingly a lot of knowledge, just not inside out, so to speak