By using the army caches on the map. They're positioned pretty well. Special thanks to pkmx on discord who spent some time exclusively studying this level and shared some insights on the official discord idle channel.
Check pkmx's discord message on 31st December in the idle discord channel if you're interested. It has details like exactly how many armies do you get from each important army cache on the Hardened Rise&Fall level. It was the conversation with pkmx around that time that prompted me to add Hardened Rise&Fall into my list of AP grinding levels.
9.5 days 11th super, need more slots, keep dumping epics. Could have dug for four more days and got a Lego but decided I'd rather just get going to the next super.
That's an interesting question. I guess it's hard to count the time because of the nature of idle games. Idle game is not like I sit there and then play it for a certain number of minutes or hours. Instead, it's more like picking up my phone and click a few buttons, and then put down my phone and continue with whatever I was doing in real life, and then after a while I pick up my phone and click a few buttons again, and then put down my phone again.
Instead of having some continuous blocks of play time which I can measure, it's more like many tiny bit of clicking being spread evenly throughout the day.