Any fuel type sitting for too long will become an issue. But for a couple months I have never had to treat gasoline or diesel. My bus used to sit parked for months withough being started and never had an issue in the 4 years and 28k miles I put it in my ownership. The bus sat the longest from January through end of March, but I always did the oil change and fuel filters before the big vacation trip to FL around new years.
In between that the bus would sit 2-3 months through the season at a seasonal site and get pulled out to go somewhere else for a weekend. Then serviced and winterized in November each year till the vacation trip.