There's already ten planets with the supposedly rare phrik on them, on this site. Yes, on an actual galactic scale, that's nothing, but in the scope of our roleplay, that's a lot. For Cortosis, there are eight such planets, according to the Restricted Materials list. Same goes.
As such, as a long-time judge, I would suggest that anyone that's looking to add a restricted material to a planet would have a better chance if they looked to the less-widespread restricted materials (save for the disallowed Beskar, as previously stated by our dear Codex Admin) when creating a planet, if a restricted material is to be included.
This however does not discount the work that needs to be done, regardless. The more quality work you put in, the better, IMO, because dang it, I want to be impressed.