I reckon you could do a lot worse than targeting horses to run a place in fields of 8-10 runners & go from there.

If relying on systems , one would need to run a few of them at once , because the better systems tend to only have a few bets each month.
i found using 4.5 years of data seems to be enpough data for most systems.

Chop the results into lots of 150 if possible, so as to give us an idea if the system has any long term legs.

I ran over 100 systems all at once, using the GTX program, at one stage.
It was very good , all systems done in a few seconds.

The trick is not to double up on runners mentioned twice, by different systems.

One would go crazy if it was done manually.

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Cheers.