I use a 55 Panasonic OLED as secondary pc monitor and to prevent burning the best solution i found was simply to put a few image gradient of greys to cycle, then the regular screensaver set to 2min. It has been almost 2 years now and absolutely no sign of burning (tested with some patterns like red which would show it clearly)
I think the important thing is to have some cycle going on, even if it's not particularly dark, as long as it's not a still image for too long, it shouldn't cause any problem. Also make sure you have pixel shifting on in the menu and the most important, let it performs the "maintenance" when you power down the TV (it has to remain plugged all the time).
I will never, ever (ever) go back to lcd's. This is an everyday amazement of oled for every type of contents, work, movies, games, and even browsing. Only have to keep in mind it's an emissive technology so the risk of burning will always exist.