Another newbie question

[miraja2]

If I am going to play a card, I do the majority of my work the night before. I probably spend an average of about 20 minutes per race.
I use this time to go over the PPs, charts etc. and I figure out what horses are absolute tosses, and I scribble a few notes on the horses that MIGHT be playable the next day.
However, I NEVER determine my actual bets the night before. When I get to the track, I obviously have the work I did the night before with me, but I wait to determine my actual wagers until I know some of the following:
1) Are there important scratches in the race that will affect the probable pace scenario?
2) Is there a track bias?
3) Is it raining?
Etc.
These are things you can't know for sure until you are at the races. If you have determined your bets the night before, you are not taking these very important factors into account.
I hope this helps.