I give a quick introduction to the org-map-entries API in this new post:
https://scripter.co/looping-through-org-mode-headings/
Day 22 of #100DaysToOffload
@temporal I'd suggest that you bring that up on the #orgMode mailing list.
I follow that list and I see that Ihor is really responsive to questions related to org-element library and caching (and almost anything Org related 😃 ).
I would have submitted a patch to improve the documentation around this topics if I knew them well enough.
But if you bring up this question on the mailing list, Ihor or some of the other core Org developers might improve the documentation.