Google Calendar - How to Set the Default Event Length
One note - if you are in a view that displays more than 1 week, the default is full day event. This default event length will only work in the day view or the week view.
(Here is a video on how to set the default event length if you prefer.)
To set this, first go to Calendar Settings (the gear) -
Choose Settings -
On the right side, select Event settings -
Look for the default duration, this is at the top of the event settings -
Choose the length of time that you want to be the default (the one you use the most...) -