What if your netadmin makes you change it every three weeks?
Edit: Whoever downvoted me obviously undermines how quickly 'password lag' builds up if you're made to change your passwords often and forced to not use the last 3 or 5 passwords again.
Particularly for sites you only log into every few months. One time passwords, with a 6 week lag between use require a password manager. Memory will not cut it.
And if you are nontechnical that means paper. I consulted a decade ago with a team that had ~5 systems like this. The office was awash in sticky notes. Sometimes security policies are a menace to actual security.
Edit: Whoever downvoted me obviously undermines how quickly 'password lag' builds up if you're made to change your passwords often and forced to not use the last 3 or 5 passwords again.