For my current story, once. I write the chapter and then look it over one more time, but that's pretty much it. The thing is, my current story is more experimental, nothing serious, though it is getting some traction so I want to experiment with it outside of Scribble Hub and see what kind of reaction I can get from it, but nothing that requires me to pour a million hours to get that one sentence right.
I am planning on writing a "real" story, and for that one, I will be rereading it a few more times. I've actually written something more robust with world building and what not. I would rewrite it like 10 times. People still found things wrong with the writing. But then again, I posted it on Critique Circle and those guys are kind of snooty about writing. No writing style seems to get their approval.
If my current story is anything to go by, I wouldn't sweat over trying to get everything perfect. As long as it's readable and the story is understandable, people are not going to care with the exception of the few who will write a review on it. I swear, for my story, I'm only writing it by the seat of my pants and people are like "I like this". it baffles me, but I guess this is part of the experimentation.
Well, that's assuming you just want to have some fun. If you want to sell the thing, get it published, then yeah, you'll have to put some work in and reread it. I guess it all depends on how much effort you are willing to go for your story and what outcome you want the result to be.