From google search .... some say 1/8 inch per month, some 1/4 per month, some 1/2 per month! Sounds like lots of variation.
I ran the clippers last saturday, no guard. As short as it would go. Today, a week later, while running with a #1 guard (1/8 inch). There was a little bit of trimmings ... that experience might support 1/8 per week ... 1/2 per month. No wonder sly guys need to shave their heads daily to keep up.
The super short or bald look is excellent! Why mess with longer hair? Guess I'm preaching to the choir today.