All jump cues have a certain distance that they are optimized for. I think of them as different golf clubs in a set. If they have an extension they may be good for two different ranges. I would say the jester is a pw and a 5 iron.
The thing I don't like about the jester, you can't jump underhanded closer than one diamond away from the ball that you are jumping over. The directions say anything under one diamond away take off the extension and jump overhanded. Anything more than one diamond, put the extension on and jump underhanded.
I've come to the conclusion that you need more than one jump cue for different jump situations. One for getting over balls very close, one for medium range, one for long jumps and a full break cue for just getting over the edge of a ball.
I use a stubby jumper for long jumps as it is more accurate. Most normal jump cues are good for medium range and I have yet to find that magical jump cue that I can jump over a ball within a chalks width consistantly.