The only thing the dealer told we was to make sure I ran the Genny for at least one hour a month because some dealer will look at the sell date and if you don't have at least 1 hour of run time for each month they might not honor it.
You don't need an hour.
But I would recommend adding StaBil stabilizer to the fuel and if you are not absolutley sure you have ethanol free fuel, use the ValvTec brand of stabilizer and ethanol treatment.
Then once a month with the stabilizer in the tank:
Start, warm up for 5 minutes - no load
Turn everything on for 20 minutes (AC's, water heater maybe a portable heater)
Turn off everything for and run for 5 minutes
Shutdown
Don't leave the fuel in there forever. When done camping for the season I make sure the tanks are full with fuel and stabilizer and then in the spring I start using that fuel for all the lawn equipment. First trip out gets fresh fuel.
Last year that 25 gallons in the Cyclone kept our portable generator running during Sandy for the first week that no gas stations were open.