I've played on chipped reeds that were adequate, but never were they optimal. In the heat of battle (so to speak), you may have to use a damaged reed until you have the opportunity to replace it. But, by the end of a scene (in musical theater) or the end of a set (in performance work), I've always moved to another one that's intact.
In a similar vein, I've yet to encounter an intact reed (in Van Dornes, at least) out of the box that was not useable. Some are better than others, but all of them will do for me.