Here's a possible new angle with small fields -

1) Neural categories of CP, $ and Dist on a setting of 3, all others on 0,
2) Bet all selections under $10 in the resulting market,
3) At least three horses to be at double figures in the resulting market,
4) Maximum of 9 runners,
5) No Maidens, and all horses with a minimum of 9 career starts,

I've looked the results from last Friday, (6 days). The Betfair results include commission deducted.

Friday
Outlay $47
TAB return $51.50
Betfair return $58.89

Saturday
Outlay $58
TAB return $65.80
Betfair return $$81.72

Sunday
Outlay $32
TAB return $34.40
Betfair return $40.78

Monday
Outlay $12
TAB return $3.70
Betfair return $3.64

Tuesday
Outlay $31
TAB return $42.80
Betfair return $54.36

Today (the faves unfortunately won almost all the qualifying races).
Outlay of $17
TAB return $12.30
Betfair return $12.83.

By my reckoning, the results over the six days are:

Outlay $197
TAB return $210 for a POT of 6%
Betfair return $251 for a POT of $27%.

The winner was struck in 48 of the 55 races.

If I get time tomorrow I will list the selections.