The first quilt class I took more than 25 years ago taught to press seams open. I got busy with life and didn’t do anything more with quilting until last year. I took a class at JoAnn’s and the instructor taught to press seams to darker fabric. I took a video class at Craftsy and the instructor taught to alternate directions to match seams. Some YouTube videos I’ve watched said to press seams open when a ‘busy’ block creates bulk. Seems it’s situational.
I’m a newbie to quilting and sewing, so I’m still experimenting. I personally find it easier to nest seams when I alternate direction, but don’t like to see dark fabric seams under lighter fabric. My newbie instincts say it feels more precise/consistent to press seams open.
interesting question.