A lot of the British elite also measure lactate during sessions.... particularly those living/training in the USA.
That said....
"All of this is to say that I’m not a big believer in magic workouts or secret training plans. Endurance training involves stressing your cardiovascular system, metabolism, and muscles in a way that spurs them to adapt. There are many different ways of organizing your training in order to accumulate as much of this stress as possible, while allowing enough recovery between sessions. The wheel gets reinvented on a regular basis, but it’s still a wheel."
....is probably the most important paragraph in the entire article.