Do a couple quick math calculations. Depending on the size of the geese, if they are small I prefer the rectangle plus two squares method where you sew the diagonal and cut off the extra. With the geometry of triangles and such, for small units there is barely any more waste than cutting triangles.
Other people do other techniques, there are many ways to make geese. Some depend on your project or your fabric or your tools.
My other option for geese is correct sized geese triangles but oversized triangles. I'm using that in the Bonnie Hunter project. Posted a picture here:
Bonnie Hunter's 2019-2020 Frolic Mystery
edit: Other people in that thread are also sharing their problems and solutions/techniques.
Although I used to be all about precision and that sort of stuff, I've had to relax a bit as my vision gets worse. What I've found is that cutting larger does not lead to a whole lot of waste, rarely do I ever have to cut more than one extra strip to accommodate an extra quarter to half-inch per unit. The speed and accuracy (and therefore fun factor) I get by my slicing and dicing and then yes, the extra trimming step, is worth it to me.
Even still, I came up with 90% perfection, 5% ok, and 5% funky little monkeys. The good thing is that the unit size is correct so it will be easy to work with, but there are a couple of points that will be cut off or mountains that lean towards one side or the other.