As a banker, I'd say it's generous and limit it to no more than 2 a year. As a consumer, of course I would assume that it would never apply to me, but would appreciate it if it ever did.
It might be easier to track if you did it on a calendar year basis; the "count" could be objectively derived from the periodic statements and readily apparent to both the bank and the customer. Fewer "conversations..."
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.