Several years ago I cut all my misc piles of fabrics into 2", 3-1/2" and 5" squares using Joan Ford's "Scrap Therapy" They are sorted into size/color plastic shoe boxes. These sizes all "Play Good" together, like 2 2" squares make a 3-1/2" square . Check out her books, I think she has 3 or so that have patterns to use these size squares. I saw recently that Moda's new precut size is 3-1/2" "Treats". We will probably see some new patterns coming out for that precut.
This has worked well for me since I cut these sizes..