I have to admit that I had to an online search as to what a waste knot was! So, no I've never used one, but in some cases I wish I had known then what I know now as I could have used it in a couple of projects. I normally just leave enough thread on the back to "stitch over" as I'm starting a new row. I also do what I call a slip knot if I'm stitching with two strands. Take a single strand of floss, put the two loose end together and thread the needle. This leaves a loop at the other end. Put the thread through the fabric and backdown, putting the needle back through the loop. Pull secure! This was actually something that Christine showed me on one of our SAL's and I use this ALL the time now.