What I have found using multiple systems is that its a strong idea to try & achieve around 24%SR on a fairly consistent basis.

This help reduce the long runs of outs.

Another thing that helped a lot, in weeding out poor value payers that barely break even ,is to delete all selections that have a price that's less than $3.20 in the pre-post market.
They tend to be over bet.
Ones SR will become lower but the POT generally increases.

If using multiple systems , try not to double up on bets where they are mentioned 2+ times amongst the other systems.
Just because they are mentioned twice does not mean they have twice as much chance of winning.

I had GTX which has its own pre-post market similar to the newspapers & It was able to filter prices accordingly.

I know that it can be frustrating at times where something suddenly does not work as well as it used to.

Apart from the runs of outs, its the lower values that kill us in the end ,so using above angles helped to get closer to making profit.

I feel your frustration my friend

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Cheers.