In reply to douwe:
> It is indeed the flexibility I'm looking for. Also I want to be able to do some training in a short timeframe, sessions with a partner do take at least twice as long typically.
Improving your aerobic capacity takes time, unfortunately. There is no substitute for long duration/low intensity exercise. If the duration is too short, your aerobic system won't adapt, and if the intensity is too high, ie, you are getting pumped or failing, then you have crossed the aerobic threshold and you are doing anaerobic training.
As Mark Twight would say, there is no such thing as a free lunch, and if it were possible to get the same results in a shorter time period, we would all be doing it. To use a running analogy, doing sets of 200m sprints alone won't help you to run a marathon ( though it will certainly help your sprint finish ).
That said, "The Self Coached Climber" suggests that 30-45 mins of continuous climbing, be it traverses or laps, is sufficient for improving aerobic capacity, which isn't really all that long.