This is for rookies. 

When milking cows, you can pick a group of 6 cows for rotation. By the time you've milked the 6th cow the 1st cow you milked will be available to milk again. There are enough cows at Olvia, Calpheon, Duvencrune and I think Grana for two people to milk at the same time as long as you both stick to your group of 6. All too often I see someone milking every cow on the field and when they see me come in they frantically try to milk every cow near my before I do as if they won't get a chance to milk anymore. As long as you've astablished your group of 6 cows you can put your mind on cruise and drain your energy worry free. Just try not to fall asleep.