How many landings per year are performed using the integrated standby instrument system?
None, as far as I have ever heard of. There may be an instance out there of failure of both/all of the INS’s or displays, but in the airline world at least, it would have to be absurdly uncommon.

It is nice to have the standby ADI as a tie-breaker between the two primary displays in case they should happen to disagree (which was more likely with mechanical instruments than with electronic displays), but actually losing everything else &amp; using just the standby to landing - between really rare and unheard of.