Well, I know there are more successful shooters than I at this type of shooting. I will tell of a few things I have observed.
1) Usually the first 30 yds the wind direction is the most important
2) mirage is very helpful in reading the last 30 yds
3) sometimes their is one predominant flag and it is the one you mainly have to watch.
With everything you have to take the into account the way things are laid out such as berms, lanes and tree density etc.