I type my 17-character password very fast. It’s a strictly automatic process, all muscle-memory.
The timing is very critical and synchronization problems happen a lot. There’s lots of hand-alternation; sometimes one hand is a decisecond early or late and I type a letter out of order. Sometimes I hit J instead of H because the “down” muscles are faster than the “left” muscles.
All these errors are compounded because I don’t actually know my password consciously. I’m not typing a word, I’m just activating a motor program. I don’t think “H”, I just put my finger “where it’s supposed to go next”. So all the error-correction in the cerebellum and motor cortex that I’ve built up from a decade of typing never has a chance to help.
Amusingly, I can type my ordinary and root passwords just fine under the influence of alcohol. So a complex password isn’t an IID for a computer.
On a darkly humorous note, many years from now, this may be an excellent stroke diagnostic. If I can’t type my password without concentrating, it’s time to call the paramedics.