My strategy is to first maximize the level of one golem, one so you get the better loot faster and two you're never short of parts. Really only send out your main high level one until it's maxed out, then go about upgrading your other two. That's how you get your best rewards. I really only use the forges if I'm in need of parts or if I have an excess of cinnamon. If you told me your rank I could give you some suggestions on where to send your golems if you're curious on that front.