Sleeve Wing said it. Be able to keep track of any situation and make the decision to change something when you are not comfortable with the situation or another crewmember indicates concern to you, or you lose track of important factors. Do you understand the traps you can fall into by doing things by the book, and how US or other air traffic control rarely lets you divert at the planned altitude and route through a sky full of planes in holding patterns, unless you declare "minimum fuel" etc? For example, if the book says decision fuel (to divert) = alternate+reserve fuel, resulting in about 10,000 lbs at the destination after burning fuel to go there from where you are NOW, you should add 1-2,000 lbs to that company figure, even if it means less holding time than you would like...
If you are waiting near the runway with all engines shutdown and tower says to start engines before you had planned on doing so, and quickly taxi to the nearby runway, do you have time to safely do all checklist items with only 4 minutes to go before the "wheels up" time ends?
Will being "mission-oriented", in order to reduce further delays to passengers, lead you down a path where important items will be overlooked before takeoff or final approach? This has gotten many people fired or killed. An IP during upgrade training reminded me that "speed kills" (the reluctance to slow things down in order to double check at a normal pace, even the nerve to decide that a simple go-around is needed etc). The real world can get us into trouble-it has no respect for what is printed in a book, or how well clearway design or met theory is understood. Some of our book figures are designed by pilots who don't acknowledge the unpredictability of "real world" situations, and might not have flown anything but a desk or simulator in years.
You might also read US books such as "Fate is the Hunter" etc by the late Ernest Gann, or the airline pilot books by Len Morgan.