I mostly agree the above posters. There's room on the site for both kinds of stories, for plots that slow build up, for nearly plot-free stroke stories, and anything in between. There is no fast-and-loose rule of "one sex scene per X words or Y chapters."
Forcing sex scenes is a bad idea. Forcing anything just makes stories worse, in my opinion. On the other hand, this is a site for stories that are at least erotic, if not outright pornographic, so your readers will expect your stories to feature sex with some regularity, and you should shape your stories in a way that naturally leads to it.
That applies just as much to stories that feature practically nothing but sex as it does to stories that spend a lot of time building a plot, characters, and world. The whole point of slow building plots, after all, is that they build towards something. In fantasy, you build towards an epic battle with the orcs. In thrillers, towards the final confrontation with the bad guys. In comedies, you have your punchline(s). And for erotic stories, the thing you should generally (but not necessarily always) build towards is sex.