What you’re describing the search engines see as a “doorway page” which was an incredibly popular SEO technique in the 90s with millions of different doorway pages created for different keywords until the search engines clamped down on them.

I would advise against use these since if Google detects the approach you could be penalized. The Google Webmaster guidelines states:

“Avoid doorway pages created just for search engines…If an SEO creates deceptive or misleading content on your behalf, such as doorway pages or throwaway domains, your site could be removed entirely from Google's index”.

So best practice today is to integrate themed, optimized pages within your site structure.