Can Muni run more express buses?

A spot.us (a reader-supported news-ish site) pitch person wonders why most express buses stop by 8:30 a.m. (inbound) and 6:15 p.m. (outbound). Also, since most express lines are jam-packed with riders, why won't Muni add a few more of these convenient buses? "Overcrowded buses would seem to indicate that there's more demand than Muni can fill with its existing express service," spot.us goes on to point out. We know we'd love more express buses. The few of them we manage to catch get us to where we're going in record time.