russ, its because sometimes we do a photowalk, with like 30 people and we all have the same starting time, so we know that each participant have the first photo taken at a certain time, but their cameras might be offset a little, its not about just two cameras and we cant pick each camera and adjust the clock, some people wont allow or dont know how to do that.
And yes we know that a certain batch of photos are offset, but we dont know how to repair that.