I get 6 mags on my vest... if I wanted to I could do another 4 on a leg.
but then again.. I'm a bigger dude... but the condor molle vest can physically mount 3 on each side.
if you want to talk how to manage them... then this is what I do:
6 mags across chest all fully loaded... need to change out in a fire fight?
mag out of the gun, into the dump pouch.
mag closest to loading hand (left) out of the pouch, into the gun.
a lull in the action or walk to respawn, empty comes out of the dump pouch, into pouch farthest from loading arm, the full mag then gets pushed towards the loading arm.
It's a pain in the ass if you are on your stomach or on your back. Though on your back is a lot more manageable.