Opiate,
I'd say it depends on the degree of wear the blade shows....
when the edge is still nice but only a little dull, perhaps they only touch it up with a sharpmaker, because this thorough regrinding job always eats away quite a bit of steel of your blade; and they don't do that until they feel it is necessary.
Why shorten the life of a knife when a touch up is all it needs?
But I am pretty sure that if you tell them explicitly NOT to use a SM but regrind the whole edge on a belt grinder, they will happily do so. At least it's your knife, your decision.
Dennis