Thanks for the links. Yes, it was Patrice's redo of the other person's tutorial.
And yes, I see now that it does result in chopped off corners. There has to be a way to to this that won't chop them. Maybe sewing a larger square to the center one? I'll work on it.
amma, I'm going to watch the video. I'm hoping that'll be the one that works for me.
Lacelady, your method is the one I did originally, though I didn't know the exact seam allowance for the triangles. I had problems with looseness where the triangle seams came together at the center square's points, so I thought I'd try this other way. But thank you!