Well clearly farm a never ending event in big grps who lagg the servers down is a stupid way of play the game and will not be sponsored by blzzard. Where is the lore/rp in that.
Do the invasions, kill the elites there you have a more interesting way of get shards and when you done those and no more events/elites up atm go do some riads/instances.
Farm a event 2-3h in a row for 30k shards, not a healthy thing for the game.
If you want a mob farm for ever go to a grind asian MMO