In the military, I got mine cut about once a month (had to keep it off the ears, "whitewalls"...the person in the link has them, but also has sideburns). Once out, I still got "buzz" cuts, but they were about 3 months apart.
There were guys who got 2 cuts per month, and others who could squeak by with every other month.
Of the pompadour I have no experience.