What have they learned that would make for a different outcome were there to be a 2nd wave before a vaccine comes out?
Giving oxygen at home based on (pulse/ox) oxygen levels. (At least in our community.)
Medical stuff:
How to set the respirators for covid pneumonia.
Tolerance for high CO2 levels as long as the patient is oxygenating.
Which drugs to give at which signs.
I'm sure more that
I (not a doctor)don't know.
And don't discount the not being overwhelmed part; the patients get more attention.