Freesites make up about a third of what I do in adult (which is about half of what I do online
). If you're looking to build a solid revenue stream, you have to have variety, and you also need to give it time.
I try to produce 5-10 new pages a day in my evergrowing porn empire and promote them or other pages too. Freesites get worked into that, but are not the only thing.
I have to say, I have yet to see the amazing SE benefits of Freesites. I have no problem getting SE traffic to sites, in fact, SE's are my forte, so to speak, but freesites only do so-so on SE's, at best, for me.