I remember reading that Barack Obama only had two colours of suits while President of the USA, because making lots of small decisions inhibited his ability to make larger/more important ones.

Decision fatigue impacts our ability to choose between several options, causes us to make impulse purchases, and can even lead us to avoid decisions entirely:

  1. Impaired ability to make trade-offs. Trade-offs feature several choices that have positive and negative elements. They are a particularly energy-consuming form of decision making. When we are faced with too many trade-offs to consider, we end up mentally depleted, and we make poor choices.
  2. Impulse purchases. When shopping, decisions regarding prices and promotions can produce decision fatigue, depleting our willpower to impulse purchases. This is why snacks are usually displayed near the cash register: by the time they get there, many shoppers have decision fatigue and may grab an item they hadn’t initially intended on buying.
  3. Decision avoidance. Sometimes, our mental energy is so depleted, we completely avoid making a choice. We may as well try to bypass the mental and emotional costs of decision making by selecting the default option when one is available.

Interestingly, poorer people are more prone to decision fatigue. “If a trip to the supermarket induces more decision fatigue in the poor than in the rich — because each purchase requires more mental trade-offs — by the time they reach the cash register, they’ll have less willpower left to resist the Mars bars and Skittles. Not for nothing are these items called impulse purchases,” explains Dean Spears from Princeton University.

Source: Decision fatigue: how a burden of choices leads to irrational trade-offs