It make sense to what you are saying, as long as the same units are doing the job function every day and the service person is initmately knowledgeable of the various operations & hourly useage of each unit & is keeping records of when the "skipped' items are due; the PM frequency is in tune with the manufactures recommendation (most are backed on normal/clean and is kept in the communication loop when & if units are rotated to another job function/enviorment. As you well now, freezers units would need an increased frequency of PM as condensation & cold soaking plays havoc with everything on the units.
If you change service guys (girls) then you get to retrain again.

Let me give it in a little better detail. As you know its not the pallet but everything around the pallet that causes wear and tear. (Operators-floor condition-hydraulic cycles specific to the site-freezer app vs. dry grocery--condition of batteries etc.) If you have an in house set up where the same guy is touching the trucks, then based on the sites conditions you may cut the time spent for pm in half for certain parts of the same make or model truck, and you may extended out the pm times for other components on the same makes and model units. If you have heavy hydraulic cycles but the units are not freezer app, you could go thru all the same make units and service just the masts and attachments and leave the steer axles and traction motors until every other pm. Is this making any sense?

I've never hear of that but based on the wording & brief description, it sounds like the customer would be short sheeted on key items for the sake of saving a few bucks. Key items, like fork wear, lift chain adjustments, oil/filter (they rarely fail but if not change will cause big buck failure), lube (mast pivots, steering axle, tilt pivots, foot control pivot shafts, etc.), just to name a few. It also sounds a lot like "break down" maintenance to me vs. planned (aka preventative) maintenance.
Just my opinion, but I haven't heard everything. Would be intereseted in more details of such a program for ICE & electric both.