What I will try to do this year when the weather gets better is just free ride to a focus duration. I will get an estimate target power from XATA and then just ride according to the terrain. Go easy in sections that get interruptions from traffic lights and when I know I have a good stretch of road ahead I will go hard. I will let the terrain dictate the duration of my efforts while I decide the power. As I don’t have a garmin I will just check the focus of my ride at the end of it and then adapt for the next time out.