When you're from our side of the pond its organising.
Say each game takes an average of 5 minutes and the first round is a race to 6. Lets say the average number of games per match in the first round is 10 that's 50 minutes for the first round, but we can call it an hour just to keep it simple.
Second round will be the same, race to 6 average of 5 mins a game, but this time the games are closer and the average number of games per match is 11 (doubtful I know, but just to be safe). That's 55 minutes/ and hour again. Now you're up to 1330hrs.
4 players left, 2 matches so its time to bump it to a race to 9. Average time per game is increasing due to all the sweating that's going on; its now 7 minutes per game and avg number of games is 15. The competition is fierce at this point and hard to seperate the field so matches become tight. That's 1hour and 45mins to complete the semi final. This brings you to 1515hrs.
Show time now and the 2 best guys are ready to joust with their cues. The final is a race to 11, average time per game is still 7 minutes because these 2 guys don't mess around, no sir. Uh oh, its gone hill hill so that's 21 games @ 7 minutes. 2hrs and 27minutes which brings you upto 1742hrs. Just enough time to shake hands and handout the winnings.
I didn't put much thought into it, and my math is probably off, way off but I think if you followed this you'd be done for 6pm easily.