When your scraps are rectangles and not strips, you can use the grid method. It does require rulers and such but back when I was still doing sew/cut precisely before switching to my current technique of sew/cut large and trim down it was my preferred method. I still use this when I'm making sets of the same triangles, like for any sort of sawtooth star project -- I keep them whole until I'm ready to work on that block and never loose any (which may not be an issue for other people...).
Here's a good site:
https://quiltsocial.com/making-multi...e-grid-method/
I used the grids in this project
https://www.quiltingboard.com/member...14-621635.html