The best time trialists (such as Miguel Indurain, David Millar, Ellen van Dijk, Tony Martin, Tom Dumoulin and Fabian Cancellara), are believed to have very high power output at LT/AT, which they can then maintain for the duration of the time trials.
To be a successful time trialist, a cyclist must have exceptional aerodynamic posture and be able to take in plenty of oxygen.
By using aerodynamic components, a bicycle can be designed to minimize its drag coefficient, allowing a rider to drop their time by minutes during a long course.
In relatively flat mass-start stages and races, time trialists often work as domestiques for their team leaders, or participate in breakaways.
Likewise, Tom Dumoulin was able to win the 2017 Giro d'Italia by defending the lead he had built in the individual time trial in subsequent mountain stages.