The version you have heard is shakier than its popularity suggests. The underlying observation, that deciding repeatedly without support degrades what you produce, holds up on plainer grounds.
The widely repeated results about judgement deteriorating across a working day have been challenged on both statistical and confounding grounds, and the broader ego-depletion literature they sit in has had a difficult decade in replication terms. Treat the dramatic version as unproven.
The problem is rarely the number of decisions. It is that each one starts from a blank page.
Reduce the number of decisions that require fresh thought. Sort by reversibility so the cheap ones stop consuming deliberation. Have a fixed sequence for the ones that matter, so you are not reinventing the approach each time. And keep a record, so the third run at a recurring problem starts from the previous two instead of from nothing.
None of that requires believing anything contested about willpower. It requires accepting that starting from zero, several times a week, for years, is an expensive way to work.
Five Peers editorial note. Sources named in the text.
A fixed sequence, so the decision does not start from a blank page.
Compose my board