Here's my test -- the package I had (I think I got when my local Tuesday Morning was one of the first to close down) had 2 strips each of 7 different colors, so I used one set so I could compare them with the others. They all seemed well cut at 2.5". In their defense, the back of the package said Do Not Prewash! (Picture 1)
I layered them into my impeller (no agitator) washer with the towels on the bottom and a 4 yard piece of yardage on top. I didn't have any color catchers but I did have an old school/well used dye grabber from back when they were cloth... While they did come out snarled, it wasn't as bad as I expected. (Picture 2). I carefully separated them and cut off the loose threads and tried not to stretch or otherwise alter the fabric. I then dried them with the towels for maybe 10-15 minutes.
Even including the thready edges, they were all consistently about 1/8" narrowert after the wash/dry. When I measured between the frayed edges, they were over 2" and closer to 2.25. Some pieces frayed more than others. The lengths of the fabric was at least 1 to 1.5" shorter! The big thing for me was the color loss in the purple -- they look like two entirely different shades after the washing, which is why I left a line of the dark purple. The turquoise also had quite a bit of color loss, the others were not so bad. (Picture 3).