I only watch cadence and HR. If I had power, I'd watch that, too. I might glance at speed from time to time, but it's not important. I use a recording HRM or a Garmin so I can download the data and have records. I don't know the stats on the ride until I download the data. I have data on all my workouts in electronic form going back 15 years and it's very useful indeed. I look back at it frequently.