Back in the day, I used to run substantially sub-11 in the 100m.
Now as a 40+, I got food poisoning at my only meet of the year and managed around 12s. Without sickness, maybe 11.4-11.5
I do all-around workouts, not dedicated to short sprints. I've found Bekele compelling, and have begun running mile workouts. For a not-all-out mile I have dropped from 6:20 to 5:20 in 3 weeks, running a fast mile every couple of days, followed by half- and quarter-mile intervals until I get tired, at 5- and 4 min/mile pace.
The mile/1500 has become more interesting to me, and here's why: for short sprints, I think you need LOTS of repetition, so that when the race happens, it is all basically automatic. If you don't have the repeats in, you will blow part of your race, and there is nothing you can do to redeem yourself--blow one part, and you flame the whole race.
But in the mile you can remedy instantaneous errors, except for a very few, if you act appropriately. Far more interesting for a guy who doesn't have the time to do enough short sprint repetitions at the track to put together a good race.
If I ever get below 5:00, I will go in a race someday--I can't wait to hear all my sprinting comrades laughing at me.
I still plan on running the short sprints on guts alone.
Any other converts out there?