Scaling has been a problem in war games since forever. I won't say how long ago it was, 'cause it's embarassing, but I started out with a book called The War Game by Charles Grant. He set out to create a horse-and-musket era tactical wargame from first principles. He got a bunch of re-enacters together and figured out marching speeds, shot off muskets as a simulated target to see how many balls hit at what range, and did similar experiments to get the basic data, then created a simple simulation based on those data. And, using that system, a refight of the Battle of Waterloo, say, took (in simulation time; it took days to game the damn thing in the precomputer era) 90 minutes. The time-frames were usually off by about an order of magnitude. This phenomenon occurs across the spectrum of times, technologies, and operational scales.
Miniatures wargames of that era used various fudge-factors to make their time scales balance. Those of you who played Dungeons and Dragons are familiar with the residue of this problem in the always-complicated-and-contentious rounds-and-turns system for tactical and strategic movement in that game.
The explanation Grant gave at the time is that there's a lot of 'stooging around' in war. And basically, at this point in my life, I have to agree. Human beings almost never do anything in a focused and efficient manner, except perhaps for playing computer games. Next time you're in your workplace, observe. You go to someone's office to ask a simple question, but you exchange a bit of conversation about the Red Sox, then you stop by the bathroom on the way back, grab a candy bar from the machine, and get stopped in the hall by someone from another section who has a question you don't know the answer to but can look up and get back to them. A game-designer building the 'go ask Bob a question' routine thinks over the process and says 'OK, walk to Bob, ask question, walk back' pulls up his movement simulator and the distance, a minute each way, adds 30 seconds for the question, and pops out 3 minutes (giving a bit of slack for to the estimate) -- for an operation that in the real world takes 30 minutes of work-time.
I bet no army in history marched a season solid. They fought someone's rearguard for a week and made no progress at all. Dysentery hit the ranks and they had to camp for a month. The commander got conflicting orders and sent a request for clarification. The ruler changed his mind about the plan of campaign and set them back the way they came. The logistics officer got a new girlfriend and neglected to send supplies for 3 weeks. Somebody decided the cavalry needed more training in the lance before the campaign starts. The panzers get diverted to Greece to bail out an inept ally and the campaign gets delayed for a month. The weather isn't right and the invasion gets put off for a month.
The universe loves us not, and human brains were evolved to tell each other where the ripe fruit is. It's a wonder we get anything done at all.