In reply to SFrancis:
For me, systematic training/cycles are insanely boring. I have no desire to do a foot on campusing interval cycles that lasts 40 minutes. Nor can I be stand under a fingerboard and work a routine for 40 minutes. It's all so tedious.
Add a weight vest and you can train harder, quicker, and get better gains (according to my heavily caveated advice, relient on anecdotal evidence and containing many variables). The trick is managing fatigue and getting enough antagonistic exercise ( gotta watch golfers elbow)
I do weighted deadhangs on 12-14mm crimp- 15 mins routine. Some pulls ups weighted - 15 mins. And occasional circuit boulder with extra weight.
Using weights for the semi focused training I do has seen noticeable gains.
If you're climbing in the 6's I wouldn't recommend, but Im punting mid 7s and it's helping.