I have a simple approach to training. Barely requires a cycle computer at all.
4 easy fun rides and then one hard ride. Easy rides are 1.5 to 6 hours in length at a pace that I can just talk and smell the roses. Hills take discipline and a small gear to keep it easy on easy days. Most easy days are 2-3 hour rides. The hard ride (one of five rides in a cycle) consists of intervals of 8 minutes duration at very specific output levels and that is the only time that I stare at the display.....on these rides. (Polarized training)
If I start any ride and if I am not feeling loose and good by certain points, I turn around and come home. You only get stronger when your body is recovering. You break it down and then allow it to recover. Breaking it down before it recovers is often/usually counter productive, which is why staring at a cycle computer and pushing gears every ride does to many people.
I even think I am going to sell my Powertap G3 Zipp 404 wheelset....I personally do not see the value or fun having it on the bike. The only slight value is when trying to maintain contact with a group on a climb, power has no lag unlike HR.....it takes about 2 minutes or so before a high power output registers on the HR meter. The power data could theoretically allow you better pace on the climb or long individual TT. I can't see the value in downloading and analysing the data after each ride. How would you normalize for temperature, humidity, wind, etc.
The only real reason I have a Garmin 800 is for navigation, I can't read a cuesheet anymore.