From: El Paso, TX
Broadly speaking, the first factor is the player
It's really this. If you have some level of OCD there's almost no limit to how much time can be spent on a given turn. Review every pilot in training every turn and swap out high skill trainees with lower skill frontline guys? Sure! Check all your frontline air units every turn for excessive airframe fatigue and cycle them in out of stand-down mode so as to reduce Ops losses? Definitely! Build a giant spreadsheet with all the in-game unit commanders (air/sea/land) and constantly check their skill against those in the leader pools so you can swap in better ones every turn (within the limits imposed by your "political point" reserve)? Of course! Tweak your submarine patrol zones every turn because, well, you can? Who wouldn't?
Rest modes, ship repairs, air search zones, fuel and supply levels at all 800+ bases, aligning weather forecasts with planned air ops, the list goes on and on and on. One week of diligent, almost round-the-clock attention to each individual turn? With this game? Easily possible. Is that actually necessary? Well, no.
Because, conversely, if you play against the Japanese AI, you could literally ignore every Allied national force except the US, follow the American island hopping model, and still pull off a victory in 1944/45 that would play out pretty darn close to the historical result. But, but, but....the Dutch, English, ANZACs!!!??? What about them? Don't touch a thing...don't even LOOK at one of their units, ever. In fact, even for the US you don't need ANY pilot training or air search or ASW patrols or new leaders, or really almost anything except to do all the ops things necessary in the specific areas which are part of your overall conquest plan. Follow this model and you can probably whip out 5-10 turns a day, probably less during a major operation. Is that also fun? Well, maybe.
The point is that you can go whole hog on the minutiae with this game or keep an extremely light hand on the reins, and each approach can be successful in the end. But as the man once said, "it's the journey, not the destination", and that my friend, is up to you.