When I try to create a new event, the default values for both start time and end time is 8:00. That doesn't make much sense. Please change the default end time to be start time + 1 hour. That means as long as the end time field is not manually adjusted, the end time should always be updated to start time + 1 hour for every start time field change.

This way, I can simply set the start time to e.g. 13:00 and the end time field automatically displays 14:00. One hour duration is quite usual for many events and therefore this approach saves time for people creating such events.