Is it a password that it is so difficult to remember, that you will type it in a piece of paper, and one day leave it inadvertently on top of your desk?
The point is: if you choose something with numbers, case combinations, strange characters, the odds are that you are not going to remember it.
If you choose many different passwords for different applications, as it is strongly recommended, rather than a single one, it is going to be even more difficult to remember.
What “human” beings will do is to write all these passwords in a single document. In the best case scenario, they will encrypt this document and protect it with a password. This valuable document, will be then the target of brute force-attacks. Note that, there is no point in choosing strong passwords everywhere else, if the password document is protected with a weak password, such as a dictionary word or the name of your dog!
In the worst case scenario, this document will be unprotected, or even a piece of paper (I’ve seen this sort of thing happened!)
The human element, is always the weakest link on the security chain; hackers know that – so THINK!