I operate 3 main systems on Saturdays, each having a very good profit.

The problem is though.. over the last 2 weeks I have had 3 selections
in 3 different races, sometimes betting each horse 2-3 units.

All races have been total wipeouts, all unplaced. Maybe unlucky..
What does one do when 3 selections are available in the one race?

Back them all?
Leave it alone?

Cheers.