If a person takes a full program
Mows their lawn correctly
Waters correctly or don't water at all (because its better not to water then water wrong)
Overseed in thin areas
Treat shades areas differnt then full sun areas
Then other then weather their lawn will be perfect (if weather cooperates)
Lawncare with cool season grasses is very simple IMO. Weed control and fertilization throughout the season is very important but water is the most crucial piece of the puzzle...period!!!!