I can do T6 in 5 minutes or so on my Monk, but trying this strategy to gear my Barb made me start to fucking lose my mind. Kadala is a stingy cunt to me.I just farmed Shards on my geared DH. I could get 500 in maybe 30-40 minutes. Pop over to my Barb to spend them and repeat. Not sure if it was efficient but leeching on public games doesn't appeal to me.
Personally, I like to leech T6s on my Barb. You'll actually get 1 or 2 useful drops every few runs that are actually useful. Most people don't mind, usually there's an uber geared Monk or DH that you follow around. win/win.