This option is reachable from the session toolbar in the modification area.

If you use this feature, the program will update the duration of each talk in this session by comparing its starting time with the starting time of the next talk taking place in the same room. The duration of the last talk in the session is not modified. You can also specify a default free time between 2 talks. Here are some examples:

before (original configuration):	after (free time set to 0 mn):
	after (free time set to 5 mn):

compute talks starting time