Model numbers and approximate prices for the clones you've tried, please. Examples of video or pictures taken available somewhere?
I've downloaded what is called the Git2 manual (pretty lame -- no specs) for the Git2 and the range of intervals is shown for still photos as 5 to 60 seconds.
This manual is only 1.8 Megs, so I'll attach it here.
I have a couple of really cheap GoClones that I've used - video quality is decent, but not as good as a GoPro.
I'm also looking for something that will take still shots at intervals too, and the Git2 might fit that bill.