ubetido, this reminds me of a system called "The old 1,2", this is taking the prepost fav as the bet IF it is TAB no1 OR 2, AND finished 1st or 2nd last start, (OR 1st up over 1200 metres or less) if not, take the 2nd (or joint) pre-post fav. if it is TAB no1 OR 2, AND finished 1st or 2nd last start.(OR 1st up over 1200 metres or less)

It is rare not to get at least one winner on any given day, though if you have target betting in mind, remember "beware"

PS. It is important that you always use the same source of pre-post fav.