I washed some 2.5 inch Hoffman cut strips. They shrunk 1/8 inch in width. This about 15 years ago.

I am not a prewasher unless I suspect bleeding. I have never prewashed a precut. I was given three charm packs that had been prewashed. A mess, none were the same size and I ended up trimming them down to 4.5 to make them the same usable size. Some shrunk less than 1/16th inch, while others nearly 1/2 inch and were wonky. The pinked edges were a no longer sharp points and I cut them all off. Poor quality fabric? Poor cutting of the charm pack? Maybe, but they were glorious colors and the fabric had a good "feel" so fussed with them and made a donation quilt with them.

I have never tried this but I recall a suggestion to soak precuts in moderately hot water then put them in a "salad spinner" to get the water out. The idea was that this would be easier on the fabric and not damage the edges. What? Who still has a "salad spinner"? I choose to just use the jelly roll or charms or layer cakes as is.

I just bought a salad spinner last summer for three reasons:

To get excess water out of small pieces of fabric
To get excess water off waahed fruits and vegetables
to get excess water out of blanched broccoli before freezing it

No one has ever a swerved this question when I have asked it:

If one has enough reason to wash a large piece of fabric, wouldn't there be enough reason to wash a small piece of the same fabric?

In theory, yes.
Whatever you’re worried might happen to the large piece of fabric-bleeding, shrinkage-could also happen to the small piece of fabric.

But in practice, washing lots of small pieces of fabric is a whole different experience, because you have way more edges, and edges fray.
I’ve never washed 2.5 inch strips of fabric because I’d be concerned about all those frayed edges, and the strips themselves knotting around each other. If I lose even a fraction of an inch at the edge, the whole piece doesn’t work.

When I wash a whole yard of fabric, I might even serge the raw edges, but if I don’t, and there’s fraying, I just cut it off and still have lots of usable cloth.

Thats just my humble opinion.

I washed some 2.5 inch Hoffman cut strips. They shrunk 1/8 inch in width. This about 15 years ago.

Was it baiks in the jelly roll? That long ago there was no standard for how a pre cut was actually cut. Believe it or not Missouri Star had the standard for all pre cuts to be the same, in cuts and amounts per pre cut name. They were buying massive bulk orders, the manufactures complied.

Forgot to add in my post. Hoffman use to have the batik jelly rolls cut by hand. It was on the package cuts may vary due to the fact of the hand cutting.

I think thet were cut by whoever got rid of them. It was a Christmas print with gold metallic on regular quilting cotton.

I pre-wash everything for two reasons: So I don't have to deal with any chemicals the fabric has been treated with or any soiling that has occurred in passage, and because I prefer the idea of any bleeding or shrinkage happening before stitching. I agree with the notion stated above, that if their are reasons to wash a larger piece of fabric, those same reasons apply to a smaller piece of fabric.

I've worked with jelly rolls twice. I did wash them. I washed them by hand, spun them in mesh bags in the dryer, and hung on the line to dry. Fabric shrinks much more over its width than over its length (just like it's much stretchier over its width than over its length). Since jelly rolls are cut across the width of fabric, they shrink much more over their length (the width of fabric) than over their width (the length of fabric). So those jelly rolls I washed shrunk a bit in width, but not enough to prevent me from using them as 2.5" strips (I think one set was pinked and the other wasn't). I didn't bother checking to see how much they'd shrunk over their length.

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).