I hate to say this depends, but it really does. If you have an older system and it's not very sophisticated, then, by all means, turn off all your loads, unplug your coach, start the generator, start your loads and try to get up to 50% load going, then run the generator for at least one full hour once a month. It's better to run it longer less often than shorter times more often.
Having said that, I don't do any of that at all. I've programmed my generator to come on 30 minutes every Monday at noon. My ATS and power management system do all the safety precautions for me and power down everything immediately when the generator is first turned on. My EMS turns on the loads gradually after the generator has gotten up to operating specs.
Net, net, don't look for advice from this forum on this particular issue. It really depends on your setup.