Heard it in Russian a while ago, it’s one of the classics. Here’s another one:

A guy walks in a pub, sits at the table and orders a pint and a thimble of beer. Bartender gets him a pint and asks why he needs a thimble of beer. “Hold on a sec”, — replies the guy, putting an inch long little man onto the table from his pocket: “Jack, tell him about the time you told the wizard to go fuck himself”

You either budget your time reasonably, or let the exhaustion do it for you.

It sometimes feels like you can do 200% of what you can normally on your “prime”, but the reality is closer to 120% + exhausted enough to make the original task smaller. And often the way you shrink/drop original tasks isn’t as good as if you do it beforehand.