Crafting Materials Value

So after opening a couple apex packs, I started to wonder if there was a way to more efficiently use the crafting metals you can get. At first thought, you would obviously want to save up and purchase a desired skin or cosmetic. Though if we were to purchase several common tier cosmetics instead, that would remove them from the pool of available items in the packs and thus give us a higher chance of rare items instead right? And if that wasn't true, theoretically, at some point the only common you'll be able to get would be more crafting metals for higher tier loot.  Or is my way of thinking flawed? This is just a random thought I had and I'm not sure how valid it is. I'd love to hear you guys thoughts