Even if you are not using her templates for a specific size block, they can be helpful as a corner trimmer if you don't have one. On triangles it's especially helpful to have the engineered corners, you just have to take note of how you are going to use that particular triangle.
Marti also makes a template specifically for that purpose, as do Fons & Porter and several others. My favorite is this one:
http://www.judymartin.com/products.c...prod=9&CatID=2 It gives you cuts for just about any situation all on one template, with full instructions. It's the Point Trimmer.