I'm not a great believer of selection systems..me i like to put in the time infront of the video and form and do my own ratings..
But i do have a friend who claims astronomical figures by Simply backing horses who have been duel nominated or nominated for the next day.
Obviously hes taken into account the trainer or owner doing there own indepth form study and finally chosing the race that suits...
His only filters are ,No maidens (obviously) ,performed on the track and at the distance..

he doesnt take horses that might have been scratched because of bad barriers or track conditions .

might pay to have a look at this and see how it performs....seems to simple to me