This is my understanding. Marking the strips and the cuts, help keep the block close to square, because we all know when you cut and sew angles, then flip open they could easily get wonky. I think if you don’t put marks and you’re off, you’d still have a block, but may have to square up to a smaller block. She’s not measuring her marks , just making registrations to align back fairly square. This is my opinion anyway. Have a great day-Toogie
BTW thanks for the video link.