Launch the calendar and go into the options, there should be an option to change the default duration. If not, keep specifying it when making an appointment.
Posted from my CrackBerry at wapforums.crackberry.com
Nothing obvious in the calendar options unfortunately, was hoping there might be a hidden option somewhere or that someone had figured out how to do it.
Guess i'll just have to keep changing it manually everytime i add a new appt.. How annoying
There is no way to change it, at least not in the Torch 9800. I called AT&T to ask precisely this question. AT&T checked with BlackBerry, and the answer is: No.