Write Down Your Password – Schneier on Security

To be clear, this advice is from 2005. I'm pretty sure if you asked Schneier today he'd recommend a password manager instead of pieces of paper.

Changing long master passwords/passphrases can be tricky.

Write them down on a small piece of paper and keep it until you'd remember it correctly if you were very tired or very drunk.

Changing once a year is about right, and rotate all other passwords too. Be sure your pwd mgr backs-up old passwords and the pwr mgr file is backed-up to alternate locations and cloud or backup keeps some past versions of files.