Anytime we need to concentrate on something and was struck, or in distracting circumstances. Casting is the majority, I will admit that, so you may have a point, now that I'm looking in the book. Perhaps we should stick with combat casting.

Yeah, we should stick to something neutral, but I kinda doubt running into other adventurers, or good aligned monsters. It's a possibility however. The only feasible thing we could use concentration for besides casting is to use concentration in spells where the checks are it's duration.

The pickpocketing thing was more of a funny idea anyway, but then again the Bardic Knack may come in handy. Probably not, but maybe.