I have used that "insecure" system for 20 years. However, over the time I added additional several additional obfuscation levels, especially for accounts with m

I have used that "insecure" system for 20 years. However, over the time I added additional several additional obfuscation levels, especially for accounts with monetary value. And then there are of course site password rules that force me to use various variations to my scheme. Additionally I use a different email address for every account. Those with monetary value are not predictable. Of course all this became unmemorizable for less frequently used accounts over the years. So I had to use a password manager. However, I store only the rule/hint to generate the email address and password, not the data itself. Could dedicated hacker with a keylogger learn my scheme? Absolutely yes. Am I afraid of any automated attack? No. I guess the keylogger is the real threat here. Once I am infected with that, the dedicated hacker can save their effort to learn my schemes. (Where I use keylogger in a wide sense, covering accessing your clipboard / browser input fields.)