[chiefalchemist]

Being efficient is not the same as being effective. Focusing on scheduling for the sake of filling time is a fool's errand.

Furthermore more, in a given day or series of days, the brain has limits. It can and does run out of gas. Those times you think "I can't think anymore" are legit and true.

In terms of true productivity "Your Brain at Work" by David Rock is by far the best thing I've read. Highly recommended if you want to think better.