I think you have to try to find out if you like precuts. Ask for them as gifts and try to keep in one range to begin with. The same as all fabrics some are better than others I used a batik which was cheap to buy, the lengths were not straight , measurements varied and fabric was of a poor quality. You get what you pay for.
You would require a large stash to put 21 different fabrics in a jelly roll.
Look at some of the precut videos in msqc in utube and make a decision as these show the variety in a pack.