Personally we run our generators 24-7 when needed for several reasons.
1. Convience, I don't own it to look at and polish it, it's a tool and I use it when I need it.
2. Health, my son has issues that require power
3. It's cold in Maine, when it's 10 degree's it doesn't take long for the temp in the house to drop and pipes to freeze.
4. It's hot in Maine, and humid. Sleeping (or trying to sleep) when it's that humid means I get no sleep, if we have a storm that knocks out power chances are I'm booked the next day doing clean-ups. It's no fun and not safe running equipment when tired.
5. Even though we have wood heat, it's a boiler, it requires power to run the circulator.
6. Because I'm on the FD I may have to leave with little to no notice with no way to return to restart the genny while away. Easier on my wife and son if I just leave it running. For what it uses for fuel, the piece of mind is worth it.
Most folks around here that have generators have a fuel supply as they know they are on their own for an extended period, so round the clock is not an issue. During an outage if I shut mine off I can hear others in the distance, even though I have very few neighbors, the few I have all have one.