Back in my day 1989-1994 on "A" models the pilots didn't drop live as often as people may think. This is mainly due to the high cost of the munitions themselves. Once a year sounds fair. It would also depend on if the Unit was a Combat tasked unit or a Training unit. Never in my 5 years on the A-10 did I ever see a Live Aim-9 fired during peacetime in my unit. The Training Aim-9s have an Inert rocket motor, Inert Warhead, but a Live Seeker Head, So I would assume the only difference between firing a Live vs Training missile is that the Live will come off the rail.
This is only in my experience though.