No you do not have to run it at full throttle. But yes hydrostatic transmissions like their rpms up. If you are working the tractor like pushing snow or cutting grass or blowing snow then get your rpms up. You don't have to be a full throttle but close to it. If you are just tooting down the street looking around and not really working the tractor then half or quarter throttle is fine. Listen to your tractor it will tell you when it is straining. Hope this helps. Dusty