What is a double square knot?

It is interesting how one technique can have so many variations :D:D:D

I use a double strand of crochet thread and a square knot. But recently I used a decorative stitch from my sewing machine that made a tiny little starburst sort of thing. I just thought I'd try something new and I really like the look of it. Each place I would have placed a tie, I just did this tiny machine stitch. My back and knees appreciated it too!

I tie all my quilts and do square knots.

Looks like the answer to this is also:

It depends - - - on what and how one wants to do it.

Seems like the main criteria is to have the ties close enough together so the batting (or middle layer if using flannel) don't shift and tied so they don't come out.

And how OCD* the person making the ties is.

*Obsessive Compulsive Disordered

I do the "up, down--up down" method you spoke of in your first post. I also do the triple tie like you mentioned. In the past I have used embroidery thread to tie my quilts but I have had them come loose :-( ....not sure why they came loose but it's a pain in the neck to have to tie a quilt twice. My grandmother tied her quilts with yarn and they are still holding strong with repeated washings over the past 30 yrs. I think I will try crochet thread, next time, like some of the other posters mentioned.