Every 24 hours of runtime would be insanely wasteful. A quick Google for a Generac manual shows they recommend annually or every 125 hours, whichever comes first. They do recommend an oil change after 30 hours to replace the break-in oil.

The Onan/Cummins LP generator in my RV requires an oil change every 150 hours or annually, whichever comes first with the first oil change after 50 hours.

Ah, I probably forgot the 1 in front. But the annual thing still stands. Every 2-3 years is not something I've seen recommended.

I believe the reason for that is no engine oil manufacturer warranties their product longer than one year.

However, engine oil these days is very high quality and should last longer than a year.

0: https://youtu.be/T-yt5a1cWd4