It depends on the individual.
For some (lucky) people, waxing can last 6 weeks. For others, there is regrowth after a week.
Also, for some people, regular waxing weakens hair growth. One of my sisters started having her legs done about 20 years ago. She now only needs them doing twice a year. Grrrrr!
Depends which area your talking about, I wax everywhere these days. Armpits seem to grow back quicker (which is attractive). Legs about 4 weeks and bikini line, about 6 weeks. Suppose it depends on how hairy you are in the 1st place and how coarse or thick the hair is.