when I bike commuted I went as fast as possible in the morning and on the way home I just went at a pace that I could sustain for the distance. going in was mostly downhill so I went with it, you know? going home was mostly uphill so I worked the climbs. I suspect that if the ride had been an equal elevation gain/loss each way, then I would still charge out of the gates in the morning, cuz that's just how I am.