Imagine I have 240 troop spaces. I fill each barracks with these troops in this order: 22 barbarians, 30 archers, and 2 wall breakers (barbarians will be worked on first, then archer, then wall breakers). This will fill the entire 240 spaces in my army camps.
Now, what if I wanted to prepare my next army?
I can add another 2 wall breakers to end because all the barracks have the same troops and thus will complete units at the same time. However, if I wanted to add an archer or barbarian to the end, they would instead go into the previous archer/barbarian stack. Thus, I will have to add the archer and barbarians after the first stacks have finished training.
Look at the Spell Factory
If I want to stack spells, say for example two Rage spells then two Heal spells, it will stick them into two stacks, one for the Rage and one for the Heal. But what if I wanted to stagger them, so that I could have a Rage and Heal up ASAP? I can just click on Rage, Heal, Rage, Heal, and the Spell Factory will create four stacks, one for each spell type.
Moving back to my previous issue--I would be able to queue (B=barbarian, A=archer, W=wall breaker): 22B 30A 2W, then 22B 30A 22B
This way, after the first 240 troops are trained, I can attack and the second batch of 240 troops will have started training.
