If you do the stitch and flip method -
The formula is: finished size of rectangle plus 1/2 inch
The squares are Height of the rectangle plus 1/2 inch
Example: You want to have 3 x 6 inch geese - cut the rectangle 3-1/2 x 6-1/2 inches
Cut the squares 3-1/2 x 3-1/2 inches
The differences:
Stitch and flip - you trim off those "excess" triangles
If using all triangles - one has to trim off those "dog ears"
Which way is easier for you?
You could follow the pattern directions just for the sake of following them - and then if you make it again, you will know which way works better for you.