I was wondering what the best way is to structure a new website in Google's eyes. Currently, it contains two top-level categories (X & Y), and clicking a term under either one will result in the URL: www.nameofsite.com/X/X type term, or /Y/Y type term

Technically, it is correct to group all "X type terms" under X and "Y type terms" under Y, but we could probably be more granular and break all articles into 5-6 top-level categories by breaking Y up into more specific categories.

Given that the current URL structure will eventually result in 1000's of "X type terms" and "Y type terms" under just two top-level categories, would it be more advisable to have several of these, as suggested?

Thank you in advance.