The system works well with 3 to 5yr. olds who are 3rd to 5th up, but I changed it to 3rd to 4th up as it's easier to pick the selections [most formguides don't show last 5 starts].

A certain amount of common sense is needed when selecting top AE after the other rules have been satisfied. There is no point ending up with a horse with the 7th highest AE because the first 6 highest didn't fit the other rules.
If I can't find a selection by the 3rd or 4th [depending on field size] highest AE that fits the rules, I ignore the race.

4. 7 to 21 days since last spell [should read last start].
Last rule should read: 'Bet only if less than $10 SP'.

Also, I wouldn't advise using this system [or any other for that matter] in NSW or tracks in southern QLD for at least 2mths. until horse fitness levels get back to normal cycle.