For example I got a 305 ghost shell in the raid but did not upgrade cuz I might get a 310 one later. Also I got a 302 handcannon which I kept but did not upgrade cuz it could be infused into something like a hung jury

Ok, I get your point. But here are my observations regarding it: 1. I have only fed a weapon that was perk upgraded, and in one case infused, to infusion 2 or 3 times. And I did so for better perks and/or stats of a new weapon. I know from the armory which weapons I like the stats of, and I know what perks I like, so it is rare that I end up replacing a weapon I have chosen to keep. 2. Also, It costs something like 30? weapon parts to fully perk upgrade a weapon right? And then 10? per infusion. All I know is that I have spent easily 80%+ of my weapon parts on infusion, not on perk upgrades.