I'm a little unclear on how one efficiently uses a generator to power highly intermittent loads like fridge/freezer.

Does one monitor the freezer temperature, and when it starts warming start the generator, then wait for the freeze compressor stops, and then turn off the generator?

Or does one keep the generator running all the time, so between times of the freezer running the generator is idling?

The second option is certainly more convenient, but seems like it would waste fuel while idling. The first option would last longer--but the generator is supposed to be kept away from the house and it could get annoying to have to keep going out to start and stop it.