The most important thing in my handicapping

[Mark]

Congratulations for your skill and perseverance. I have never won a Pick-5 or Pick 4 for that matter. I have never bet one. I have a hard enough time winning one in a row.
That said remember Doc's warnings about becoming rigid in your rule making. I personally don't subscribe to use "Last Line, unless.." or "Best of the last 3 comparable" paceline selection routines. There is a reason that they publish up to 10 lines for each horse and it will often tell you the horse's story as well as what his trainer has tried to do to improve him.
In areas of the country where the horse populations at the track are stable and the field sizes are relatively small more restrictive paceline strategies are can be useful. But in others where shippers appear as well as horses off layoff or with a race or two off an extended layoff, the last few lines rarely tell the whole story except that the horse is getting conditioning that will allow him to run back to his previous good efforts.
Seasons of the year will often bring in new horses as trainers shift their stock from track to track as well as bring them from the farm.
With your dedication and work ethic, I am sure that when these things occur you will study and digest the information presented.
I can only refer you to the greatest handicapper of my lifetime, Jim Bradshaw, in his 5 step approach and his work with Richie P on the Hat Check blog. Look at all the 10 past performance lines and determine which line represents the likely horse's effort today given the projected pace and the horse's running style. Each race is unique. One size does not fit all!