In reply to Tobias at Home:
With stonefall and seracs there sometimes little, if anything, you can do to climb safely.
Loose or snappy rock can be assessed and judged, and you can then choose which holds you weight, and in which combinations, to keep the climbing within your risk threshhold. This usually means doing far harder moves compared to if you were prepared to trust everything. Or backing off if you're not convinced it will work.
I've climbed a lot of routes with dodgy rock and very very rarely ever fallen due to pulling off holds. Yet seconds following have often pulled great chunks off and gone flying off into space, because they had the luxury of being able to pull on things without checking them as carefully.
Despite appearances it has almost nothing in common with Russian roulette.