I only press seams open if I am working with very narrow strips, half inch or less finished width. I press to the side even where multiple seams meet, in the center of a star for instance, because I spiral them to eliminate the bulk. With sharp pressing, all seams lie flat...and that's without pounding on them with a hammer. SID is not technically possible (nor acceptable in competition) with open pressed seams since there is no 'ditch' (lower side), but I think many quilters now sew right on top of the stitching line instead of a thread or two to the side of it.
Why do I press to the side?...By pressing to the side I guarantee the seam threads will not be visible thus giving me wider freedom with piecing thread color; I save the hassle of trying to smoothly press quarter inch seams open; I guarantee nested, matching seam intersections; I can smoothly flip from setting the seam to side pressing without putting the iron down; I assure that wool batting will not peek through seam lines; and, for many of my quilts, I want the added dimension of higher and lower areas that side pressed seams can emphasize.
Like so much with quilting, it's a personal choice. Even if pattern instructions have a suggested pressing plan, you are free to do entirely as you choose.