When copying events, have more than four options for minutes (15,30,45,00)

To create a new event you have the choice of selecting a start time down to the specific minute. However, when copying an event you can only select time options that are...

15 minutes past, 30 minutes past, 45 minutes past, on the hour.

We have events that require a 20 minute past start time or a 20 to the hour start time. Whenever the event is copied, it generates the additional step of having to go back into the event to edit the timings because not all options are available when copying.