Diamondgeezer, the point is that once you've done a great many offers, the chance you will be significantly below or above the EV line reduces.
Say after ten offers the chance that you'll be over 50% away from the EV line is one in twenty. After 100 offers its just one in two hundred. After a thousand offers.. etc etc. Of course, one guy in 20,000 is going to be very far from the ev line by pure fluke, but it's the sort of chance that's negligable. (For me, as soon as a chance gets lower than the chance of dying tomorrow, it becomes totally negligable ).
But I agree with Andy this discussion has probably just about run its course. It'd still be interesting to see EV graphs from anyone who has them. Me I keep terrible records so nothing from me unfortunately! (I only keep the important record, overall profit!)