To check bridge form, I suggest a tile or other clearly marked, symmetrical floor. Place your hands and feet so that they form a perfect rectangle, your feet and hands mirroring each others placement on the grid. My friend with a (presumably) normal spine finds no difference doing them like that or just going by feel. When I do this, I feel like I’m twisting to the left. That means that when I’m doing them otherwise, I’m probably not actually be aligned correctly. Furthermore, to me it implies that people with scoliosis may not know how their spine should feel when they’re straight. This has been helpful for me, personally; my back feels great after bridging, and it gives me a greater awareness of my lower back and spinal column.