I remember reading a forum member's statement that "the slowest speed in the highest gear = the best fuel economy" and with some variation based on overall driving conditions "the faster you get to that speed the better"
I believe this means that you want to spend the greatest amount of driving time at the most efficient speed ad if by going fast to get to this speed you will be forced off of it by road conditions then fast is not good but if you can get there and stay there then fast is good.