This method is doomed to fail.

A horse's credentials is "relative" to its competition in a race.

You cannot hope to win, backing horses, by judging them on their own merits, without looking at the competition. In other words you have to assess all the major chances in a race. More often than not - your stable horse will not be the best horse in the race.

Therefore you'd be better off without a "stable" and just assess each race on its merits without clouding your judgement with personal bias towards a horse.

Good punters are objective - they don't have any particular bias towards an individual horse which this method encourages.