Force speed is a power that many Jedi learn, as is evident by the fact that even Obi-Wan was able to run as fast as Qui-gon even while he was still a padawan.
Darth Maul used it rather extensively in a later novel "Darth Maul- Shadow hunter". He was running to catch up to his quarry who was in a speeder about 30 feet above ground level. To the persons amazement, they looked back and saw Maul running 5 times faster than an average human could run. Since an average male speed is about 14mph, that means that Maul was running approximately 70mph, which is faster than the six million dollar man.
Of course Steve Austin could basically run for decades without getting tired since his legs have nuclear power sources. Knowing how intensely Maul trained and his relative youth, he could probably go for quite some time before getting tired.
As to why it's not used more often, probably have to ask Lucas directly for that one. I guess it's simply that the particular story lines don't call for it as much, though I would surely love to see it used more often myself.
There could also be the whole draining effect that others have mentioned too, but I'm not sure how much weight that holds as Yoda also used it quite a bit in the tunnels under the Senate chamber when he was sneaking in to confront Palpatine in Revenge of the Sith.
When Yoda used force speed, he was able to run a good bit faster than a human at full speed, so probably 20-25mph or so, which was enough to evade and dodge the Stormtroopers that were after him. So if someone at Yoda's age could use the power with no mention of getting tired, then I'm not sure if that's really an issue or not.
Since he was going to confront Palpatine, I doubt that he would have done anything to drain himself extensively before what he knew was going to be a massive fight.