vbmark on "Advantages/disadvantages to multiple meta tables for a Wordpress app?"

I am working on a web application where I am using Wordpress' EAV. But not from a post, page template or plugin; this is my own stand-alone page.

What I cannot figure out is if there are pros and cons to adding all my app's data to the usermeta table or should I create a separate, custom meta table.

I will have users that can log in and let's say, for example, that each use can enter a list of planets and each of their planets have countries and each their countries have states.

I know I can just put all this in the usermeta and use keys of planet, country, and state. But would a separate table such as wp_planetmeta provide any advantages or disadvantages?

Or, would it be even better to create three separate meta tables such as wp_planetmeta, wp_countrymeta, and wp_statemeta?

I cannot find any information related to this issue. Side note, I do not need to query on the values.

Thanks.