Have to say, I agree that decision fatigue (or ego depletion) is extremely knackering. I routinely stick simple non-decision-making items like 'drink tea' or 'water plants' or 'check postbox' in at intervals on my To-Do list and it does help. I met a senior citizen lady when I was on my first backpacking trip; she told me that when she was travelling, she liked to go see a movie occasionally to recharge her batteries, as it was 'two hours when you don't have to make a decision.'