Nor did the introduction of numbers and symbols make passwords any less vulnerable to "brute force" cyber attacks in which a computer cycles through every possible combination of characters to guess a password.
"Much of what I did I now regret," Burr, who is now retired, told the Wall Street Journal. "In the end, it was probably too complicated for a lot of folks to understand very well, and the truth is, it was barking up the wrong tree."
He added that the advice to regularly change passwords was mistaken, since most people end up altering one character, such as changing from "username1" to username2", which does little to stop hackers.
In 2015, GCHQ advised companies to stop resetting passwords, saying the inconvenience it created outweighed any limited security benefits.
The original password guidelines from America's National Institute for Science and Technology written by Burr have recently been updated to change the old rules.
They now advise that people use long but easy-to-remember "passphrases", a sequence of words that do not need to feature special characters or numbers. Using "horsecarrotsaddlestable" would take one trillion years for a "botnet" cyber attack to crack, compared to one minute for "P@55w0rd".