Grub,

The rules of NB where all linked to produce a sensible handicapping result. Every selection must have a chance, a runner I would consider backing after handicapping the race and within reason this has been achieved. I think a big problem with many systems is they are designed by very poor handicappers with little understanding of it, through lack of interest and not much practice because of that. The system then throws up a lot of selections that a handicapper wouldn't back in a pink fit.

You could use $3/$7 as your price for most newspapers etc. But I think $2.50/$6.80 is a good one for the WA site. For the Newspaper if there is a $2.50 or less PP fav. I don't back a selection running against it. For the WA site I use $2.40 because the site has those sort of odds. Newspapers tend to round to 50c.

There is a starter today at $2.50PP. Might ease out up to $5, or shorten. That one is heading to wards odds-on. I don't worry too much as it evens out. Another runner today is $6.80PP and running against a $2,50 PP fav form the WA site. $2.40PP and I would have ruled out the selection. Small differences but put in place over time.

You really need to work with what suits you, but be careful of worse than dead tracks and PP odds. Also worth considering is the formline that adds to 9 for most selections didn't come from slow or heavy tracks and thats the Handicapper thinking here and saying system logic becomes rickety and unsupported by inclusion of wet tracks, unless the selections are then handicapped for the cond't. and that is drifting from the whole point of a stand alone system.
Everything must be supported by everything else in the system. I stick to 'good' tracks and less bets in poor weather. Of course, how individual punters use or modify the system is up to them. They might improve it or vis-a-vis too.