I like to leave it in until the blocks are together, it stablizes some of those angled pieces and I like the line for to sew on. There are times when I am tearing off paper and I think 'I could leave a lot of this' But then I keep tearing. I do leave little bits if they don't rip cleanly. I also, will remove a little bit before then putting the blocks together espeically if its going to get trapped by connecting seams. I read a tip about using the back side of your seam ripper to score long the stitch line on the paper. It does make ripping it out a little easier.