Mike,
That’s one of the advantages of the Structured Workout feature from TP, it packages up your one custom zones as part of the workout (dynamic). The free workout library (swim workouts and all workout) is static. It just says “Zone 2” and relies on you to memorize your zones.
Remember, 4 years ago there was no structured workouts and everyone had to not only memorize their zones for Pace, Power and HR, but memorize the entire structure of the workout!
David