About three weeks because I didn't do it all at once, an 11/12 pitch is tiring to work on. One week per side of stripping/waterproofing, then a couple weekends of shingling.
Edit: the stripping took a week from having two layers of shingles, first layer was cedar than asphalt.
Took a day to take all the tiles off the front, add insulation, membrane and batten it. Then another half day or so to put the original tiles back on
Back took slightly longer because we had some alterations done but it was just over a week in total effort
In some areas when big enough hail or storms goes through a town 1 or 2 crews will jump on the insurance payouts and take the low bid if they can do them all at once. And within a week or two at worst the entire neighborhood or small town is reshingled.
That and saving $20 000 or so in labour. I was quoted $8000 just to remove cedar shingles not asphalt as well (off-hand by a buddy). This is in $CAD.
As well as doing a better job than most of the roofs I've redone, whole lotta hack jobs on roofs since you'll never see the problem or deal with it till the contractor is long gone.