It takes about 25-45 seconds to do a scan with this option in my tv-shows, and it works for the episode in question + refreshes metadata for about 6-7 other episodes - same ones each time.
I'm gonna label those as problem eps, and check naming or whatever - perhaps remove them and readd them.
If you don't mind, I'll quote your answer out in the general public, so others may benefit from this if they have this need.
