Layer cakes, jelly rolls, and charm packs are pretty much all I have - I only buy yardage of fabric for the borders, backing, or binding of the quilt. I really like using the prepackaged fabric because it is cut in sizes that lend themselves to quick piecing, and more importantly for me they are color coordinated collections of fabrics. It really takes the guesswork out of it for me when making a quilt. There are many books out on the market which are written specifically for using charm packs, or jelly rolls, or layer cakes. I'd suggest getting one or two of the books and seeing what you think. I think they're great myself.