Many years ago I pre-washed a bunch of fabrics at the same time. I measured all of them before and after and YES different fabrics had a different shrink rate. I no longer have the details of the experiment, but I remember the outcome well enough. It was not all one manufacturer across the board ... some Moda's had more shrink than others, ditto for some of the other top brands. It was "scattered" ... but there was a lot of variance between the least and most amount of shrinkage.