Who says there's no reason to pre-wash?
.... then consider this ....
Before washing .... one metre of 60" cotton
After hot water wash/dry #1 ... one metre by 56"
With that much shrinkage, I thought I'd see what happened with a second wash/dry. No change in size.
That's one inch gone for every 15" ... hhmmm?
I bought the piece as a test for a OBW/SAW/4PP. It seemed to have a lot of fill in it and I was suspicious and wanted to know if I'd have cheesecloth or what? After the shrinkage, it's a nice tight cotton and yes, I'll probably buy the yardage.
Though if I'd sewn it and later washed .... not sure I'd be happy!
Of course, each to his/her own! :)