Im sure that if someone is really looking for a clan, that person will at least look the entire first page before turning away from this section.
with that said, i dont think theres a need to religiously bump your threads like 20 times a day. they are on top, everybody can see them.
No, you won't get more applications for your clan the more you bump your thread. In fact, i doubt that the 2-3 clans that continuously (and needlessly) have bumped their threads over the years even got more than 10 applicants from doing so.