It'll always be funny to me when an anime gets announced and in one season it likely catches up to manga that's been being released for like 3-4 years by that point.
One panel in manga can contain the information of half a page of an novel.
A minute in a anime can convey the information of a few pages of manga.
Manga is usually monthly, anime is usually weekly. Also take in the fact that anime doesn't do a 1 for 1 of everything presented in a manga (Nor does manga for a novel).
Once you know that, it's not at all surprising how anime catches up so fast.