[Mark]

The use of a consistent methodology is one of the keys to successful handicapping. As Bill points out he is prepared for the occasional losses that result from applying his methods when applying universally. However, I suggest that while we can never win all the races we wager on, reading and understanding the conditions of every race, understanding the context of that race can aid in increasing the win rate.
Jim Quinn wrote prolifically 20 -30 years ago and was commonly found in the Turf Clubs of Southern California tracks. While i never subscribed to his methods wholeheartedly, what I found most interesting was his concepts which were mostly derived from Result Chart analysis. I am not sure the name of the particular book, I think it was "Handicappers' Condition Book", I still have it in some box somewhere in the house. What struck me was the type of horses back then that he felt were most favored to win NW-1X Allowance races. These were lightly raced horses with the fewest failures at that condition. In the last 20 or so years I have confirmed some of my own observations based upon this concept. 1) Horses that break their maidens early in the year or in a meet, are invariably best animals. 2) Horses that move through their conditions early in the year and meet are better animals. In the Southern California circuit back then you had most of the top barns west of the Mississippi. Whether pointed for the SA meet that began on Dec 26th each year or as the result of innate speed, those winners generally were the most brilliant, the fastest horses that went to the lead and widened. Each month beyond, the quality of the horseflesh that won these races and moved through their next condition were just not as fast and relied on the Pace Scenario to get the wire first.
My point is that if you consider the context of the race you are handicapping in selecting your contenders, then apply a consistent use of your proven methods you can elevate your win percentage.