This question already has an answer here:
Is there any way to find out which packages you have loaded in your preamble are actually being used given the (La)TeX that follows?
I don't believe I'm looking for
\listfiles, since as far as I understand that would only return the packages called in the preamble (and whatever packages those packages may have, themselves, called).
What I am seeking to do with this is cut down on unused packages in an unwieldy preamble. I know that I could comment out each package and look for errors, cutting the packages that can be commented out without error. I'd like to know if there is an (at least semi-)automated way to accomplish this same task for when the number of packages is large.