I do not double stitch or back tack as that's the way I was taught. So far I haven't had any problems with my seams coming apart.

Nope and have never had complaints about quilts coming apart. I even recently had to repair a quilt I had made for my son 10 years ago because it had been washed so much the binding was coming off but the seams were intact. I do use closer together stitches and the only backstitching I do is on the final border since there are no intersecting seams.
Have seen a couple of customer quilts coming apart in the seams a little bit because they did use a smaller stitch. I would say that may be the most important piece of piecing, shorten your stitch length.

I don't double stitch. Occasionally with a complex shape I'll make one backstitch in the seam allowance to help hold the shape when I'm putting it together.

I do not double stitch unless I have a very lose weave fabric. I also do not back or fix stitch my seams unless they are the outside edge for the finished quilt or block. The seams inside the block or quilt have the next seam keeping them together. But the outside does not. Good luck with what you decide.

I had never thought of it. I know some of the seams on a quilt my mother made for me have come apart.

I do not double stitch, and have not had a problem with stitches coming out.

I only back stich my rag quilts at the beginning and end of joining blocks, at beginning and end when joining rows, and all the intersections - there is lot of layers and this helps stabilize them and prevent some of the shifting.
Since I do a lot of chain piecing I generally do not backs stich. I have fix feature on my machine but hardly ever use it.

YES, I double stitch for durability.

No I do not double seam but do back stitch on my outside edges if I do not use a border.When I load quilts on my LA that do not have a border, if the seams are not secure they may pull out.

I don't do either. I do use a very small stitch. If you turn the pieces right side up and pull on the seam and can not see thread it's good. I use a size 2 stitch on my machine and it is perfect.