Results for today where:

Vic. Park [good] R1 Fav. $1.50. O/Lay 1unit. Return 1.5units
Canterbury [good] R3 Fav. $2.50. O/lay 4.5units. Return 5units
Sandown [slow] R3 Fav. $1.80. O/lay 4.5units. Return 3.6units
G/coast [heavy] R1 Fav. $3.90 [big field] O/lay 1unit. Return 3.9units

Only loss was Sandown: 0.9 of a unit loss.
Total outlay 11units. Return 14units. 3unit profit. a reasonable POT if backing all these tracks.

A 4 race progression would be a bad move considering expected payout range. 3 races max.
Naturaly, better odds could be obtained that those above and would probably add a unit or two to profit.