On any shoot, documentary or real-time shoots especially, time is precious. There can be a sense of "hurry, hurry, get the shot," which can lead to hasty decisions and headaches later in the editing studio. I regularly find myself wishing I had spent more time on one shot or another rather than rushing to catch the next action. Sometimes it is better to miss a few seconds of one action to make sure you have enough of what you need on the previous.
For documentary-style filming, setting up a "desired" shot list in advance can help put your mind in the right space. Granted, the need to catch all of the action is important, as you might not know what will happen at any given second, but slowing things down and controlling the set as much as possible can help minimize this. Spend the extra ten seconds on a b-roll shot, have your talent wait while you get a better position, adjust that light or flag, and tell someone their arm is blocking the action. It makes a huge difference in the long run and leads to easier editing.