I don't use metal for repairs, as I can afford the time to set a timer and come back later if I lose a tank or two (or all...currently stuck on Devonis final) in a battle. Keeping the factory slots running all the time I'm not asleep and upgrading via relationship points takes all of it. I don't get any truly amazing PoC score to get any outstanding number of candies...just 40 per week for top 10%, which is about middle of the pack for what I'd consider the group of active players.

Of course I would like to have more candies, but the metal already can't keep up with what I've got.