Sometimes you've done all the strip mining you thought possible, and caved to your hearts content and you've run out of ore to mine in an area.

You could have any block tagged as ore have the possibility of spawning if at least 5 blocks away from air and is not within a certain range of other ore

I think there are mods that do this (slowly respawn the ore in an area). It's possible tho. I'll keep it open until I can investigate how hard it is (should not be too hard).
Possibly based on level 5 villagers.
Possibly based on monsters

This looks possible. I'll probably do this.