NB LaTeX can do this too with the \include command and maybe a \SchoolName that you reset for each letter. (This is how I make different versions of my CV for different things without having to make the same change in multiple docs every time I add something.)

Yeah I had a “public-facing” one that only had published things, and a “job application” version with had papers under review or in progress.

That sounds like mail merge to me! :) I would have perished if I had to maintain / distribute different versions of my CV at any point in my career, esp job market...