The endgame for me is by far the largest time spent on. I have to sit for hours each level to just draft.

Is maxing hospitals a good idea? i usually go to all hospitals level 3

It’s called idle for a reason buttercup. Jokes aside, no, hospitals are worthless

Even without Phase 4 advancements (hospital boost, army cache boost, auto draft) you should be able to complete nearly all levels without running out of mercenaries. There are a couple notable exceptions (Triskelion, Hardened China, Hardened Europe Huge).

To do this, the critical phase is between the 2nd/3rd market (read: alloy value +30% tech) and the final hospital. During this phase you want to capture as few territories as possible. Go straight for hospitals and merc camps. Do not mess around getting caches (you want the +50% cache tech), territories (you want max hospitals) or bonuses (the bonus is negligible)

You want max hospitals for as many territories as possible. You should be capturing in bursts (i.e. grab 2-3 hospitals, wait 2 or 4 hours for upgrades, grab 2-3 hospitals, wait 2 or 4 hours for upgrades, etc.

Only once you have +50% cache tech and max hospitals should you take on the bulk of the level.

I play without urgency. Check in, check status of tabs, stock up for a while, then claim territories en masse.

AFAIK, for all levels, maxing the latter half of the hospitals is profitable. But the first half are sketchy after the first few levels and can become unprofitable. You need to do the math to know if there is value in upgrading or not.

"Profit" means:

x > y

where
x is cost of buying all the armies from merc camps that the hospitals could save you
x = m * u
m = cost of mercs
u = # of units required to clear the map (# of units remaining

y is cost to upgrade (max out) the hospitals
ths = total hospital savings = t * hs
t = # of territories remaining
hs = hospital savings (increase in armies savings per captured territory from a hospital upgrade)

I prefer to distill and simplify. Fog Buster reveals the path. There is no way you're not calculating something anyway, FB eases the pain.