HM based service is the most cost effective/equipment friendly way to go. We've all seen the over SM'd truck, done every 30 days because that is what the CSR wrote and had the contract signed for..
If the dealer/service company has been doing the work for a while it should be easy to look at the history and work out a useage sheet - i.e. Lift # 1 averages 100 hrs between services every 30 days. Lets do it every 2 months. Lift #2 averages 250 hours a month and needs to be sm'd every month.
The service comany should look at the hours of use, the operating environment AND the age/condition of the truck and make those recommendations. I used to service a brake manf company. We serviced the lifts every week not based on hours of use, but to clean the radiators of carbon dust to stop them overheating..