I would venture that for the vast majority it is very close to 2 hours per day, regardless of event. Example:
Elite marathon runners run around 120 miles per week, which is about 17 per day, or slightly less than 2 hours. This gives them an average of say 10-15 minutes per day to do core work, drills, plyos, and weights. (realistically, they probably do these things over 2-3 30-minute sessions per week, rather than doing small amounts every day).
There are guys like Brian Sell, who run more like 140 per week (some weeks more, but 140 is pretty typical), but I'm pretty sure Sell doesn't do very much supplemental work (I heard someone say his only strength training is lifting soil bags for Home Depot; I don't know if that's true though). So basically he's running an extra 20 miles per week while his competitors are doing strength/plyos/etc.
I'd venture that 5k/10k runners, 800/1500 runners, and even sprinters allocate similar time commitment. Only they spend less time on mileage and a little more on the speed/technique strength training.
Thoughts? Maybe 2 hours per day is just a nice sweet spot?
Interesting to note: I bounced this 2-hour idea off some professional skill-sport athletes, and they said that, although they do spend closer to 3-3.5 hours at training sessions, they spend a lot of that time standing around while the coach explains a drill, or teaches them a play, or whatever. They said that if all their trianing time involved perpetual motion, 2 hours is probably what it would be.