My tendency is that if I enjoy the story, I purchase it.
Part of that is due to my justifying being involved with fan translations with the argument that it helps prove there's a market... so if any story I'm involved with gets licensed, I buy it.
I look at JNC as a bridge between fan and pro translations, a blending of both environments.
You get the regular posting of sections, and the knowledge that at some level the author gets financial return from it.
I joined JNC initially as a Patreon type of thing, a means of helping make sure the bottom line was met so they'd stay in business; it was a while until I actually started reading the prepub releases, etc.
Anyway, if I enjoy something on catchup, I treat it as a try and then buy situation.
If I don't like it, it was a premium I decided I didn't want.
It's a weird way of looking at things, I suppose.
There's also that JNC isn't just a firm publishing books to me, it's a place I hang out, and I want it to prosper so I can keep hanging out here.