In Chap 4, you def want to get Needles of Tempest wonder down for sure. It not only produces barracks troops faster, but buffs your light range. Sometimes killing faster saves troops because the quicker the battle concludes, the less rounds of damage your troops take. Specifically for light range though, if you buff them enough, they can kill enemy mages in just one shot, which gives you a BIG numbers advantage for the remainder of the encounter. However, the speedier your barracks, the more armories you might need to take advantage. During the day, you might make more troops, but you lose the overnight backend. For example, if your overnight is 8hrs and your barracks takes 3 hours to finish, you're not making troops for 5hrs. If you speed up your barracks to 2hrs for full queue, you lose 6hrs of idle on overnights. In early chapter, if your Needles is too high, you won't have enough space for the extra armories so you would benefit if you are able to reload your barracks queue often during the day. Once you get the Bulwark down from chap 6, you don't need as many armories as the Bulwark is like a super armory that never changes footprint but will extend your troop production queue. With Bulwark, you might be able to cut down on number of armories and use that space for other things (for down the road since you're only in chap 4).