This is very much a placeholder as I do not intend to make this game but thought to record the idea like a jotting in a notebook.
I have been inspired by talking to a gaming mate who just finished a History PhD on the subject of the different ways the British Army in Burma and India in the Second World War undertook its training. After reading Slim's "Defeat into Victory" I was struck by the effort, time and energy Slim put into training his army. And I am also familiar with a similar amount of effort put into the training of the British Army in World War 1 on the Western Front.
The game would not just be about the training. I don't think that kind of administration would make for an interesting game. I would include training as one of the factors and resource hungry factors in a long term campaign - like say the Western Front, 1916 to 1918. I would also have another factor that of the learning of doctrinal tactical lessons that would require a payment in blood and possible failure and then an expenditure in time and resources to distill the doctrinal lessons and then put them into the training schools so that they new units in the next campaign would be more effective. Hopefully.