Where does the Apple Workout app "save" completed workouts? The Apple Watch Workout app offers an option to "Save" a workout when it has been completed. Where are such saved workouts saved?
You can view all your past workouts (per day) on the iPhone Activity app! It gives you all the same information you see when you save the workout on your watch.

You can also view past workouts in the Health app (Workouts data in the Fitness section).