This drives me crazy, I can't use any other screen besides the workout screen when doing a workout because I constantly get nuisance alerts about being outside my power band while trying to do or see something else. Its super annoying. If I wanted to see exactly what my power was, I wouldn't be on the map screen trying to zoom or pan.
It would be amazing if they could implement some kind of vertical "barber pole" on the left hand side of every screen while in a workout with the same color scheme as the horizontal bar on the workout screen. You wouldn't need any numbers and the nuisance alerts wouldn't be necessary. That way you could see if you were in your designated power zone while still using the data on other screens.
As it is implemented now I cant really use more than one function at a time without it driving me completely insane. I can either do a workout, or navigate, or see my data, but not any of the two at any one time without the other feature completely destroying the other. If i'm navigating during a workout, the turn instructions clash with the power zone instructions and produce so many alerts that they all lock up the screen.