Just out of interest, I use to know of a successful punter whe would rate only his top 3 selections.

He would then total the percentage of the three horses as per his prices, and if that total was more than the market total of the three horses then he would back all three.

For example, if his ratings had horse A at 35%, horse B at 15% and horse C at 10% then his total was 60%. If the bookies' market had horse A at 30%, horse B at 20% and horse C at 5% the total would be 55%. Even though horse B was 'unders" he would still back all three but would reduce the outlay on A and/or C and put the extra on B.


Edit - I forgot to explain that in the above example he would bet $60 assuming $100 was the amount he wanted to collect. But as he now expected to collect $105 because of the total "market over" of 5% he would juggle the $60 so that whichever horse won he still would have outlayed the total of $60 but would've collected $105.