What size job/machine
What machine do you propose to use? That's going to make a big difference, as is the size of the job.
I have a 2-metre (6'6") Koro FTM with a verticut reel and I can make one fairly aggressive pass over 4,000 sq.m. in about an hour and a half. But I guess you would be using something like a 10 hp Ryan Mataway or (not a real "pro" tool) a 5 hp Ryan Ren-O-Thin, both with an 18" working width?????
Turning the Arab deserts Green