Jump cues
I don't want to rain on anyone's parade, but determining the accuracy of a jump cue can not really be made with 'rail' shots, or with the object ball within 8" of the pocket.
Put the object ball somewhere around the center of the table, and perform a jump shot where you have to cut the ball 30 degrees or so, and note how many times out of 10 that you make that shot, and how many times you hit the ball but do not make it. And how many times you fail to get over a ball, depending how close the cue ball is to the jumped ball.
I have only known one player, actually the father of a good friend and player, that could use the 'dart method' jump a half a table or more, and make balls with a resonable degree of accuracy. To me, the dart technique seems so foreign.
It is extremely difficult to tell if your technique is just not on, or whether the jump cue just doesn't perform right.