LOL, welcome aboard RFF1010. One of the great things about this sew along is we each get to do it our way! And there are plenty of Bonnie Hunter related UFOs, mystery or not.
It never occurred to me in my early days of quilting to trim my subunits... I will make them fit!! Now it is part of my way of doing things. There are definitely parts of the things that I do that I don't really appreciate, but appreciate the final outcome. So, I have friends who pretty much never pin -- I always pin, every 2 inches or open seam whether I need to or not, I get better results. Oh yeah, quilt police take note that I press open. Each year I think -- Bonnie gives very good directions, maybe I should press to the side. Each year I do it my way which also includes cutting large and trimming down. Boring yes, a good time for a rotary cutting board (I haven't found mine in the move stuff yet). But ultimately, this isn't typically a speed process for me and I usually have plenty of time per clue.
Teen, I don't use any special rulers. With my vision issues, however, I will often put a tape line(s) to help me be as accurate as I want and/or to help with special cuts.