I was toying with it last night, the 4-mintues does seem like a good bit too little, even if you had a dozen friends. But maybe the update today will change how much total downtime there will be, so 4-minutes wont be too bad.
Something that I didn't get to test twice, I tried rearming field supplies in my C-47 at a different field than it originated from for the strats. The strats are ringed by ~3-4 airfields at an even distance, so depending on which way you passed over the strats or which of the 5 centers you're focusing on, the closest one would change. I didn't think twice after droping one package to fly stragiht ahead and to the closest field to resuply, only it didn't work.
I honestly don't know if this is intentional to prevent a resuply exploit or if maybe I inadvertantly salvoed it out or left the bombay door open when I went AFK and my cat did a barrel roll on the keyboard. I'm going to try it again, barring it wasn't my cat, it could be a little bug maybe.