I have sewn for more than 60 years and started using leaders about 10 years ago. The bigger the machine the more problems I seem to have with it pulling my fabric to the bobbin side. Older straight stitch machines don't have huge holes in the plate and were not much of a concern, but as machines got bigger and fancier, I have had to use leaders or I end up with a wonky corner when I start. I often use cut-up paper to get started rather than fabric pieces. I prefer the paper because I can keep little pieces cut up by the machine and they NEVER get pulled in.