I think the first Nagoya Hammer was successful precisely because it wasn't a tournament. The scenarios were good fun (even if I was teamed up with Jus

It also attracted a lot of people because it was two days which makes it seem worthwhile in making the trek to Nagoya for out of towners. I wouldn't have gone all the way down to Beppu if the tourney had been a one day affair.
The mighty Prime also has a good point about the physical limitatons of having more than one game per event. While gamers that play Grey Knight Termies and WFB Chosen of Khorne may have no problems lugging around two armies, spare a thought for the poor IG/Skaven players out there. Last time out three guys came up from Kobe and stayed in a capsule hotel overnight, not exactly tonnes of spave to store armies.