I'm not in total agreement.
If the general is responsible for everything, then yes, it is burdensome for him. However, if you split the turn-by-turn responsibilities between, say, four marshals, then each of these marshals will not have but a fourth of the burden the general had. They will have nearly just as much. Yes, the more you manage, the more data you have to analyze and the more orders you need to send out, but that's not the core of the burden. The burden is actually being there early enough to give out orders. In fact, it's easier to manage an army of 30 nobles than an army of 7, because odds of getting early scout reports are significantly better with a larger army than a small one. And often, one can't/won't issue orders before having these scout reports.
Yes, distributing responsibilities lessens the general's burden. But it's more of a multiplication and transfer than a diffusal. Instead of having one guy who is so active and risks burnout, you'll need to find many. And as a general, whenever I would try to use this diffusal of responsibilities rhetoric, I'd often have to give up because I couldn't find anyone to do a decent job at it.
And I tend to view time zones as irrelevant. What matters is turn change, and being able to log in at that time. People wake up, work/study, and go to bed at different times, even within the same time zone, the player base is not homogenous. What's important is when the player will log on, not what time of day it is in his part of the world when he does.
That is the nature of responsibility in any form and situation. Taking the responsibility of one person at work for instance and splitting it between four people does not result in each shouldering 1/4 of a burden either. The burden that is directly affected however is not really the planning, but the pressure to never miss a turn.
