My MH sits (or did sit this year) from Oct to May. I did not start the diesel motor during that period as I had minimal insurance and could not take it on the road. I did start it and take it for an hour run in May.
Most "experts" agree that you should only run the motor if you are really going to bring everything up to temp. Running for 10 or 15 minutes on the motor could do more harm than good.
The diesel genset was actually used this winter for over 24 hours during the winter during a power outage in the S&B - otherwise it to is not used until the spring and then under load for an hour.
I do add a cold weather additive to the diesel each fall, just in case I do need the MH or genset during the winter.
I grew up in farm country and most diesel vehicles were just parked in the fall and left til spring. Some of these were decades old!.
Now that I am retired I expect to use my MH year round but still sit in one place for several weeks (down south!) during the winter.
Chris