Yeah, the only time you need to be anal about tire pressures is in the snow (or sand). Otherwise, find a pressure that you like on the trails and don't worry about it--it'll be fine on pavement. If I was planning a 100 mile pavement ride, I might add a couple of psi, but short of that for shorter rides, mixed use, etc, it's not worth worrying about. You'll expend more energy pumping the tires than you'll gain back any sort of efficiency improvement.