How endurance athletes train, when they train, and the intensity and duration of that training all affect the gains and adaptations they see.
Proper interval execution is essential to see the expected progress. How you analyze and interpret all that data is equally valuable. Of course, training needs to be planned so it fits into any given season, race schedule, and lifestyle. Off the bike, the importance of strength and conditioning is often neglected.
This is training. This process is what athletes live for.