I have a "King Kraft" generator that was given to me by my dealer when we purchased our Springdale TT (11 or 12 years ago now). The company that sold them gave them to the RV dealership as give-aways because King Kraft evidently was going out of business and he just wanted to get rid of them.
I did research on that generator and even posted comments on these forums way back then asking for opinions. Everyone, and everywhere said it was junk. Well, for "junk" it sure has been a piece of "good junk"! I had it worked on only 1 time and that was when the pull rope spring thing broke and my local lawn-mower repair shop put a new pull rope (thing) on it.
I keep the gas fresh in it, use StaBill in it all the time as it does not get run very often. I keep the fuel petcock turned off and run the engine till the petcock runs out. No fuel in the carburetor that way.
We don't use it for camping as we always have electric hook up. But we do use it at home for those random power outages we have (Summer storms, and Winter blizzards). When starting it, I turn the petcock on to start the fuel running again, and wait 5 minutes. Every time, first or second pull, and it fires right off, never missed a beat!
About "exercise", well ... I fire it up when I remember to. I have several gasoline engines I attempt to "exercise". My goal is to fire everything up at least once a month. But sometimes it's much longer than that. Once running, I let everything run about 10 minutes, turn the gas off everything that has a petcock and let it run till the carburetor is out of fuel.
I have a push lawn mower, 2 John Deere riding mowers, 1 generator, 1 snow blower, and 1 log splitter. When all of them get fired up in the garage at the same time, it's really "sweet music to my ears!"
Here's something to think about? If you have a lawn mower, either a riding lawn mower or a push lawn mower .... every time you fire up your lawn mower, fire up the generator at the same, plug in a light and let it run abut 10 minutes. If yours is a gasoline engine, then there's really not much difference running the generator the same as running your lawn mower. Think about that.