If your Speedy is running fast (or slow), can you trust the chronograph to be precise or will it be just as off too?
I am not a watchmaker, however they are both powered by the same "engine", so if general timekeeping is off, so will the chronograph be as well. There could be scenarios where the copuling between the chrono and regular watch section is slipping, but if the latter is slow, than both will be.
Generally speaking the chronograph is only as accurate as the base watch is. Having said that, the accuracy of the watch can be affected by having the chronograph running, and it's possible that introducing one error will "correct" the other error...but that is just luck. But unless you are timing very long duration events, or your watch is running really poorly from a timekeeping perspective, it really should not have a huge effect on a short events timed with the chronograph. Cheers, Al