I used to go until my cams changed orientation from where I have them marked, or the feel of the bow changed. But a few years ago I had a yoke loop break right before full draw. Each side of the yoke has half the number of strands, so should be replaced twice as often as bows without yokes I imagine. I estimated I had about 30k shots on them, I obviously pushed them too far. But for my other bows it's pretty obvious when something changes and it's time.