I have "made it up as I went along" with a few quilts, not really intending to, as I find it much slower than actually following instructions! But things happen -- like my latest quilt which I had intended to do following a magazine pattern. I started out fine, made up about 12 of the 18 pinwheels required and then found they did not fit into the rows as per instructions. No wonder -- the instructions said to cut squares five and one quarter inch -- when I checked the internet for the magazine I found an error message that said 5x8" squares of each fabric! (If I had used my brain I should have thought that 5 and one quarter inch was a rather odd size to start with) So I had a choice either to scrap the work I had done so far, which I was enjoying, or continue somehow modifying the pattern. So I ended up with my own design. But I am a bit mathematically challenged, so don't use graph paper -- I cut everything full size out of newspaper to try various layouts -- fast and cheap and much more likely for me to be accurate.