Idea: set barracks to train the same army every time.
If you don't understand here is an example. Imagine you can set your barracks to fill your army camps with the same amount of each unit every time. You set your barracks to fill your camps with an army consisting of: 10 giants, 50 barbs, 50 archers, and 50 goblins. You go to battle And use 3 giants, 34 barbs, 27 archers, and 13 goblins. When you come back your barracks are filling up your camps automatically. After the troops are done you now have the same exact army you used last battle! This idea would save time because you wouldn't have to manually pick which units to train every battle.