I only change a password when I forgot it and locked myself out. You only get so many trys. I do keep a list on Excel and update it but sometimes I forget to do that too.
Sorry, I'd have to agree with the wife on this one, as I have a 'black book' too. Yes, a burglar can access it, and is free to do so, as long as he understands the risk involved of invading the lion's den. I am more concerned with the cowardly script kiddies that want to invade someones PC from a nice safe distance, where I got no chance of playing cat & making them my mouse. That's why I keep a black book, and will never use an app to store passwords. The fatal flaw of your method is if someone guesses your password, he has pretty much guessed all your passwords, and I'd suspect the password in use is none too complex, which would be an easy go for a password cracker (https://spyadvice.com/password-cracker/). There is a good reason why most do not have one key that opens all the locks, turns on the car, turns off the burglar alarm, etc.
If a hacker is out to get info...chances are they are not Guessing your passwords...there are programs used to hack even most secure sites....guessing would take forever. But using complex pass words are suppose to aid in making it harder.
You're right, those programs used to 'guess' your passwords are called 'password crackers', and you can read all about them in the link I provided....lots more if you choose to Google it. Complex passwords makes it harder to 'brute force' it, provided you do not use any words found in a dictionary....there are password cracking apps just for running every word in the dictionary multiple times to break it.