Exacta Wagering

I started to research the potential of my recent brainstorm (Exacta plays using the partial box method explained in my recent forum post). Initial results indicate that it may be something to research further and tweak a little. The theory is ok, but in practice, it’s clear then when our top 4 includes a longshot (10:1 or higher) that almost always becomes a key, both top and bottom. Using a longshot as a key might be counter-productive and create long dry spells! Might be we have to overlook races where one of our top picks is greater than 10:1 (as an example). Still researching, so if you have any input please share. Thanks!