As I understand when we REGISTER (I am not talking about creating custom post types) custom post type WordPress not saved it in database. It is just a code. Why WordPress does not save it on separate table?
Why WordPress does not Use separate table for register the custom post types?
Table name : wp_post_types Columns : ID, Post Type (Ex : Posts, Pages, etc and custom post types) and many columns for other fields like slug, etc.
So WordPress can store
wp_posts table instead of post type name.