In reply to deacondeacon:
the thing is, climbing endurance is movement specific, so if you spend lots of time building endurance going round and round and round and round, you will get very good at traversing endlessly, but not going up and down. Whereas if you do circuits that incorporate up and down as well as traversing, you will work the whole lot.
That is the theory, I think, though in practice traversing is probably better than nothing, and there aren't so many walls at the castle where you can do effective stamina circuits.