Thanks, @deeelling, @lauritaylor, @brianallen, and @kseniya for your responses. It’s always interesting to hear solutions to this age-old problem.
Rules of thumb are very interesting and thank you for sharing them. As Kseniya described, I suspect many printers rely on less mathematical methods such as intuition. For instance, if a certain job appears more challenging to print, a printer would sense this and reasonably cut more paper.
Unfortunately, I have a conflict and I won’t be speaking about this issue at the Ladies of Letterpress conference as planned. That said, I still plan to explore this topic and will write here when I post material online. In the meantime, please keep this thread going if you have other approaches to cutting paper prior to printing.