It's one or the other. Darned if I can remember which. It would be easier to remember one password, but having a single password is poor security practice and inconvenient for periodic changes on sensitive systems and networks.
Few people can remember a dozen regularly changing passwords, but anybody can memorize just one.
For certain users, Password Master could be the hottest Microsoft Windows utility program on the market. I don't recommend products that encourage people to write down their passwords, but many users do and then tape the paper to their desk drawers or keyboards. A highly secure place to record passwords is a practical security move. Password Master is primarily an executive tool, because agency managers are the likeliest to need a place to keep dozens of seldom-used security and alarm codes, confidential phone numbers and personal identifiers. All my children I have no trouble remembering a few passwords.