Full means that it has the capability to playback in RT at full quality. Checking to render stuff that is tagged as FULL means that it will render it, even though your system, card, etc. can play it back at full quality in RT.
Doesn’t mean it won’t skip a beat and drop a frame. I check every render box and if I hit option+r I want everything rendered. No guessing. I hate those silly check items almost as much as the problems that fill this forum because they default to being unchecked.