Thanks Beton for your stats that show that 80% of winners come from the first 5 lines of betting but I still maintain that there is insufficient value in these horses. For example, on your figures you would have to average $3.21 on the favourite to break even, similarly the break even averages for the others are $5.17, $7.11, $9.54 and $13.08 respectively. Note these are the average price you would have to get. I am fairly sure that the TAB prices at least would be about 15-17% less than these for horses on the first 5 lines due to their take and rounding down.

It has been shown that punters overall get the chances of a horse winning right and horses win in proportion to their starting price (adjusted for the take) and of course this applies the other 20% that I look at as well.

My thesis is that it is easier to get over the odds on the longer priced horses than on the favourites. To start with the effect of rounding down is less on the longer priced horses. For example, a friend and I have a system that looks at longer priced horses. Today I backed Mini Maizing on Unitab and got $40.60 but my friend at the track jagged this winner with $81 from the bookies. I did not get value like he did but I was still happy with my win all the same.

It could be argued that applying filters to horses in the top 5 lines will improve the POT but I feel most filters either lower the average price and/or
ruin the strike rate and thus make little change to POT.

These are just some of my thoughts based on punting over the years. It is good to read lots of ideas like those on this forum because you never know when you might pick up an idea that really helps improve your own system