I don't buy precuts for that reason. I'm very picky about every block being perfect, the precuts I purchased from a LQS were not all 5", some were larger and some were smaller . I found jelly rolls have the same problem. I sold them at a yard sale and now cut my own. I guess if your not fussy precuts are fine. I have seen quilters at retreats that use all precuts but they don't really care if the rows are perfect.