There are times when even I do press to one side, like with curves and arcs. But also some fabrics are better treated that way. In my historical view of "why do we go to the side" it also corresponds with a time period when US made fabric was rather flimsy but you will find references to tiny seams on tightly woven goods. Fabric got better (in general) but we didn't change our ways of "this is how we do it because the fabric is flimsy and I don't have an electric iron" but just to this is how you quilt.

I'd say "quilting suitable" fabric is entirely suitable for open seams or by definition, it's not really quilting suitable.

So some fabrics because they ravel might be better to one side or the other disregarding the fabric. Some weaves of fabric are different and the fabric just doesn't want to fold back in one direction or another but it is still usable.

I always press seams to the side easier to nest seams. I never quilt less than 3-4" apart. If more than that I worry about bunching. I have used W&N not warm enough for me. For my quilts and some others I give away I use hi-loft polyester batting. warm in winter cooler in summer.

No right or wrong way to make quilts or quilting.

I press open too, when it's required to make certain seams look flatter, and I've never had a problem with it. I do use a small stitch length and stretchy polyester threads and have never had my stitches pop.

Closer quilting will generally strengthen a quilt. You want to make sure that the quilting is consistent or you'll have some unevenness to your quilt. I have been watching a show on thread painting by Terry White, and she densely paints in places, and then creates what she calls "environmental debris," which are little tack-downs around her quilt to help balance out the more densely quilted places so they don't look "warped". But in general if you commit to dense quilting, you should make sure it's balanced throughout the quilt.

I haven't read all the comments but to be honest I think open seams are fine as long as you shorten the stitch length. I think there is a lot to be said for open seams rather than to one side. I've done both and my open seam quilts haven't fallen apart.

I always press HST's open. It makes the 'block' more balanced when trimming to a perfect square. The reminders above to use a smaller stitch is appreciated!

I watched a video that said to press the seams open on a HST, then if you stay on the right side of this little triangle of fabric, you know you haven't lost your point.

I am a mostly press to one side person as I really think it does help keep the quilt together and I make mostly quilts that are used and thrown in the washer and dryier....and It does make nesting the seams together easier as you can feel they are locked before stitching...I have longarmed other peoples quilts who pressed opened seams and have had to repair the seam....but I think they used a too long stitch too....I don't do a lot of quilting for others...just a few.

Think about it- Pressed open, or to one side, makes no difference in joint strength. It's still two pieces of fabric joined by one stitching line. To add strength to the joint one needs to top-stitch next to the original seam, capturing and securing seam allowances to one side- as in french or flat felled seams