I've seen it mentioned a while back that the material distribution is related terrain, but in my personal experience I don't think this is true, or at least not to the extent it could be.
For example, only this week I spent hours exploring craters for Polonium and found two in 6 hours. The following day, on the same world. I find 5 in fifteen minutes of driving across a featureless plain. To me its completely random and has no bearing on skill, challenge, or a need to build up any geological foreknowledge of what is where in game.
Have a look at this video linked below. Its of a crater that is nearly 100 kms deep, it has mountains 40 kms high, and ravines just as deep. Not only is it an awesome place to visit, but its probably one of the most challenging places to explore in an SRV.
Now if places like that had an abundance of the rarest elements, and players were rewarded for venturing into them to locate and retrieve those elements, that right there throws adventure, risk, reward, skill, and challenge into what is currently a mind numbingly boring grind fest for rare mats. Have such materials only spawn in those kind of locations, but reward players for their efforts to retrieve them and we start to move away from the uninspiring random and shallow gameplay that we currently have.
I don't expect it to be easy - I expect it to be challenging and interesting... and above all... a rewarding experience both in terms of the adventure undertaken, and the ultimate goal of coming back with a few of the items I went looking for. Gametime well spent.
Waiting for a lucky random spawn to pop up nearby offers none of that.
https://www.youtube.com/watch?v=ekLvhPpOyUs