Sorry to disappoint you but I believe your method will lose long term. It is what I have seen many tote punters do. Stand out the favourite with a selection of other horses. Tote favourites wreck trifecta payouts because the tote wins every race. There is no simple, easy mechanical way to win at trifectas by just checking the tote prices shortly before they jump. I wish it was so easy. Then I wouldn't have to put in many hours of form study each week.