... And when I start using phrases like... it's time to go home.

I keep up an internal monologue while I'm working, just sorta making sure the stuff that I'm working on makes some consistent sense by going over it verbally as I tap along.

When my internal monologue starts to include phrases like "Well, this server's been around long enough to have had the patch crapped out of it..."

...

It's time to contemplate giving up for the day.