Apparently I am not allowed to reply to myself to add details to my previous post, so I am making a new one:
The time allowed to one picture should be less than 1minute, thus we are speaking of adjusting the white balance, the contrast, the histogram, this kind of basic operation that an expert can do quickly. Sometime we may also need basic retouching like removal of red eyes or electric wire in landscapes. But nothing fancy like removing wrinkles or adding a reflection in a mirror.
I believe you could do a minimum of 100 photos per hours ( I tried it myself and I am not the best expert), and let's say we speak of a volume of 1000 photos per month.
Any taker ?