I know one, who do the same thing in a larger scale. This guy make 4-8b per day... I don't have the time for that and it doesn't works when you only play in the evening like me. And you must manage more then 600 orders i think.

Topic:
I like to "farm" isk if i can enjoy the pvp/oreverythingelse after that. Thats the reason why I search an efficiently build/setup for max isk/hour. Short work - long fun.