This is actually the sort of situation where I think specialization becomes important. Once you've reached a certain level, if you keep hammering away at the full body, you can end up spinning your wheels. Or in the quest of greatness, piling on more and more volume til you burn out.
I find that you can expose the muscle groups you specialize on to a lot more volume than you normally would without burning out if you're only doing enough with the other muscle groups to maintain them. Of course, this is going to vary depending on your own recuperative ability. But that's how I avoid burn out while still making progress.
I still think taking time off completely periodically is important.
