TwoBets, my place plan over nearly 5 years ave divi= $1.64, so all pretty well fancied runners.
The first 2 years were at supertab divies only, the rest as I outlined b4, using Sportsbet, half= best of 2, the other half at unitab, which DEFINITLY showed an advantage, so I guess the real figure would be close to $1.70.

My thinking here is the amount of times that 2 totes are paying $1.04, and the other $1.20-30 or even more.
Trying to guess right up to the off (as you appear to be doing is just "TO HARD" I reckon you would be better just splitting the stake over 3 or even 4 totes and settling for the average!

But as a fellow place better you have my attention, if you want to trade ideas, my e-mail is lumbasakabayo@hotmail.com