Banks in the US are required to make you change your password every six months. And you can not use the last four previous passwords. The logic behind this is that it is supposed to make your account more secure. I find that it does the opposite. Changing your password frequently will make most people use something that is easy to remember or write down their current password. I prefer to just use one really strong one that I have memorized.
A corollary is people that right down safe combinations and leave them on their desk or carry them on them. Anytime you have a password written down someone can use it. Even if you have it stored encrypted electronically it can be hacked. The only safe password is the one that stays in your brain and nowhere else.
Every one of my employees that has access to my security system has his own unique code. Whenever my system is accessed it is logged and I receive email and text alerts allowing me to see which code is being used. Your security is important and everyone should always be aware of theirs.