I can't help with the 4-in-1 method, my usual favorite method is the rectangle and two squares. For the start of my cutting I'm going to be using some of my leftovers from the last round, some of my fabrics came to me as 10" squares via fabric swapping way back around Y2K. I made 2 units last time and have a strip large enough to cut 2 pink triangles this time, but not enough for 2 rectangles. The way I do the cut large and trim down is to cut the large triangle correctly, and then I oversize the two smaller ones.
I can say that the measurements she gives for cutting a square in an X to make four geese (you want the X and not the diagonal cut so the long straight edge is on grain and not bias), is the correct/standard size. As are the measurements for the rectangle/square methods. They are true sized -- just be aware if you are using strips for the large triangle to measure so you snub off the top of the triangle just like she shows in her pictures -- if the top is pointy you will be scant.