When people say 50% is far too great a percentage because of lack of profit. It all depends on the total take for the day/week /month. If you had someone consistantly knocking out £400 a day for you, I'm sure you could run a profitable business and keep one very happy bunny employee.
Not saying that i'm running to these %'s but you get my drift.
I think the majority of people would be chuffed with an employee who consistently knocked out half that 5 days a week