It is fine to use charm squares, however I wouldn't because it is too much clipping for me. I do mine a little different because even after carpal tunnel surgery I have a problem with the clipping. It is impossible for me to clip a whole rag quilt after it is finished. I put together the first 4 rows and then I clip the clip the first three seams. I also clip the seams in between the squares on each row. Then I add another couple of rows and clip. This enables me to clip only a few rows at a time and my hands can handle this. When all of the rows have been sewn together and clipped, I then do the row of stitching along the outside edge and clip it.