Yes unfortunately you have to check the fine print. The numbers do vary. I bought some Kaffe Fasset jelly rolls. There were only 32 fabrics. Also they were cut with a pinking shear and every strip was about 1/4 too narrow. More like 2 1/4" than the 2 1/2 they were supposed to be. Luckily the pattern I was using it worked out ok until I tried to add some strips I cut myself. I had to trim them all down to make them work.
I also agree that I often only like about half of the fabrics in a pre-cut pack. I rarely buy them.