Something that's likely to come up in my game is the PCs taking on training the city hoplites/city cavalry to a decent standard. They are aristocratic men who train individually, to various standards (so are varying degrees of skilled as individual combatants) but basically never drill together. Looking good on the sands of the palaestra or winning laurels in competitions is the motivation to train, not actual fighting in war.
Thus if the PCs took them on, their job would be around teaching them to fight as a cohesive unit, not teaching them to fight at all. I could see it taking longer than a month to learn formation drill, but a trainer only being able to handle 50 men, when they can already do the fighting part, seems rather small.
My fundamental issue is that I only have one PC with Manual of Arms II, and only being able to train 150 hoplites working them hard all winter seems a rather small number.
Essentially, I'm wondering if there should be multipliers available, in terms of the numbers who can be trained. Perhaps you can train twice as many men who already know how to fight?
Maybe you can train another 25% more men, for each supporting trainer with Manual of Arms?
Perhaps having Manual of Arms II should allow you to train more of the previous types (lights) than someone with just Manual of Arms once?
Thoughts?