I started a new forum thread dealing with crafting smelting strategy
https://www.warzone.com/Forum/568266-new-warzone-5140-smeltingcrafting-guide#Reply

I know, we agreed on the fact that unlocking higher phases isn't the first priority you should have, but I just did the math: With the new hardened levels (and assuming you start them even if you haven't reached their recommended level of advancements) you can in theory reach phase 4 with a single play through. Though, I really wouldn't recommend this, as IAP would be (except for 300 additional AP) the only thing you would invest in in phase 2.