I try to minimise the number of passwords that I use in order to facilitate remembering them.

Intruder alarm at work required a password that I had to remember and could not alter,but I altered other passwords to match the intruder alarm. I have since changed job, but the password is in regular use for a number of purposes and reliably memorised.
I purchased a number of combination padlocks, set them all to the same number, it is the last four digits of a previous employers phone number.
With a little thought, numbers of passwords can be much reduced.

There is a lot to be said for useing the phone numbers or birthdays of living or deceased relatives as passwords, ones OWN details might be too easily guesed.

Most internet forums require a password, this should not be readily guesed, but I see no harm in use of the same password for multiple forums.