Forgive me if I am wrong, but does different squad sizes not train for different lengths of time in the barracks? My observation is that if I train more troops, be that by way of more troops in a squad or having more squads (more armouries) training time lengthens if the barracks training speed stays the same.
Squad size has nothing to do with training squad size. If you build more armories/Shrooms/Bulwark, then the training size increases and the time you need to train does lengthen.
But increasing your SS does not increase training squad size, so it does not lengthen the queue.
However increasing your SS makes it LOOK like it takes longer because the same number of troops now represent fewer squads (because the SS got bigger), it also makes your army camp LOOK smaller, because you have fewer squads in the army camp, but still the same number of troops. Since your squad size has nothing to do with tourney/spire, SS has become a completely arbitrary number of no importance whatsoever. But it always looks very important, because it is very prominently displayed in the army camp. Abandoning this number entirely would make it much more understandable for the average player. Simply display actual unit numbers, instead of this silly squad size that does nothing of importance anymore nowadays.