Those are some valid points. I had one touched up today and he seemed to know what he was doing. There wasn't any burs or discolor on the teeth.
How many times can you sharpen a chain?
It really depends on use, Type of wood, clean or dirty wood, metal content, user experience, etc.....
But on average I'd say your looking in the neighborhood or 8-12 touchups, less if you have to straighten a tooth out.