Thanks @bobbypriambodo. It’s been more of a general sense of this happening for me, and has been highlighted by my friend just installing several opam switches from scratch, trying to find an OCaml version that worked for the packages he needed. As such, since the most recent experience is my friend’s, I don’t have a detailed log, but I’ll try to pay attention in future.
The final comment my friend made on this matter was that installing packages one by one would cause many repeat recompilations, but listing all the packages on one opam line did only one set of recompilations. Perhaps this is a sign of depopts then, as @antron stated.