It really seems to be a matter of personal preference. I like 1 1/2” strips for my string quilts. :-)

If all your strips are 2.5 inches, you can make one like Jenny does.
My strip quilts are made with any width, from 3/4 inch to 2.5 inch. When I am sewing strips to a foundation on the bias, I found that when I get near a corner, I would really like a larger piece so that the seam is not so close to the corner. I dug into my scraps and found triangles that were cut off other projects, and they were perfect to put on as the last piece in the corner. That makes a really cute pattern when four of these corners end up together.

I really like the Amazing Jelly Roll Quilt by Three Dudes. You sew strips together into large squares, then cut them on the bias both ways. A lot less waste, so easy, and they look fantastic. And you can use strips of any size for these, too.

Ummmm...would someone please define a string quilt for me? I keep hearing about them, but I am not sure what makes a string quilt versus not a string quilt. Thanks!

A "string quilt" is, to me, just another way of using scraps--even if they are narrow. There is no denigration in making a string quilt, just a great way of using up those last bits of your scraps.

I agree. I use 3/4" to 1 1/2 for string quilts. but if you have gigantic blocks, 2.5 would work...but I would cut them in half. (ouch)