Lochte uses fins, trains 3-5 miles a day, and he swims slow so he can focus on technique

From the New York Times: Even though Lochte has been swimming since he was 9, he has not yet perfected his strokes. “I spend more time on stroke mechanics now than I ever have,” he said.

He also spends part of each practice slowing things way down.

“The only way to really work on technique is to swim very slowly and really think about every little thing that you’re doing,” he said. “How your body is positioned, what your hips are doing, the positioning of your shoulders and hands and feet.”

His coach is mindful, too. [Link]

As for me, most of my gains have been the result of improving my dismal technique incrementally.