If you use iCal you probably have lots of one hour meetings, not because they need to be an hour, but because that’s the default amount of time a new event has and people’s tendency is to not adjust that.
Just as simple as that!
I don´t think it´s a good idea to turn every schedule into a full one, as Noah writes in his article. But he´s is absolutely right in moaning about the bad software we use, to plan and schedule meetings for ourselves and others. Give it a read!