There is a Make Default button at the top of the interval creation screen on the iPhone. If you tap this then all future intervals of that type that you create will be clones of that interval.Just a quick idea: I just created a new 5-3-1-3-5 interval workout and it would have been great to clone elements of a workout. Would be cool to see the estimated workout time, too
The app has estimated time/distance remaining metrics that can be shown during a scheduled workout, and which use the performance for previous intervals of the appropriate type. However it doesn't show an estimated time when creating a schedule. No-one has ever asked for that before. It sounds a good idea but it would require using previous workouts and exactly how to use that data would be complicated and subjective, which I try to avoid.
If all intervals have time-based durations, or distance-based durations with a target pace, then it would be pretty easy to calculate an estimated total time. But if there were any intervals that were not easy to calculate a time for, then I would probably get questions about why the estimated time didn't match the actual time.