I have yet to experiance burnout with tabletop but that has more to do with my relative newness to the hobby. Being a shy child made getting a group together to play with near impossible (Glad that's all over). However, one of the people I've found to play with has told a few stories of it. The way he talks it gets pretty bad and can end up ruining friendships when handled poorly.
The best comparison I can make is putting down an MMO. Runescape, WoW, Guild Wars, lots of time dumped into them. Haven't touched any of them in years because of the burnout. Stayed out of guilds for the most part so I could fade off without ruining anyone else's plans. Realizing that this happens to me a lot has ruined my enjoyment of the genre for better or worse. I miss them a bit but none of it really mattered. The rules you layout for avoiding and dealing with it are well thought out and helpful. It makes it a little clearer why you started making your own system.
The big thing with burnout is that dealing with it well really comes down to being prepared and knowing that it exists. A lot of people who have really catastrophic burnout don't really know what it is until they have a moment half-way down the path where they're like "Ah, I'm burning out" but at that point a lot of the remedies are a little too late.
Yeah, MMO burnout is real too. I actually thought about talking about it for a while; I've never been much of an MMO player, and I tend not to play any one thing for a particularly long time, so I'm not as familiar with it first-hand, but it's a similarly big issue.
The funny thing is that I've pretty much always tinkered with my own systems (I was introduced to tabletop roleplaying by 1km1kt, which is a hobbyist community dedicated to making free games), but it wasn't until I started having to deal with burnout that my games became decent. It's not a destructive, entropic experience necessarily, but rather something that's just part of the package, like soreness after you exercise too hard.