I'm not the fastest guy out there, so speed is pretty much irrelevant to me. I live where the geography is very flat, so climbing is irrelevant.
Mileage is the only barometer I have to judge if I've ridden a lot, or a little.
Or maybe I should just log hours ridden? I could log onto the forum and say I rode 55 hours this past month, or whatever. Next month I'll shoot for 60.