Shoto,
In reply to your question about excepionally fast or slow times effecting the daily track variant the method I use is to simply ignore any unsually fast or slow times on a particular day.
In this way a horse that has run a particularly fast time on a (say) 'slow' day will be rewarded when it's adjusted time is calculated.

to Punter69
We all acknowledge that there is no way to calculate all the variables in any one race but if you choose to ignore times, beaten margins, etc just how do YOU select the best horse in the race??????