Lets say you have ticket 1234, and you setup billable time two hours from 10am to noon.
Then you work on the same ticket later in the day, from 2pm-4pm. If you add a note and change the time, it does update the calendar notes, however it does not add an additional entry onto the calendar.
And then you work on it again a couple days later for a few hours. It only updates the original calendar entry notes, but not additional calendar entries for the time frame stated.