Add a soft constraint to ensure that no one rock star speaker is speaking at one time, which results in an overcrowded conference room with many people lining up outside.

Each talk has a crowdControlRisk level, for example 0 (none), 1 (some), 2 (a lot) ...etc
Talks with a crowdControlRisk != 0 needs to be scheduled in pairs of 2 at the same time.
Never 3 at the same time. Never 1 at the same time, unless it's lowest risk and there are an odd number of such talks.

Popular talks soft constraint:
Popular talks in big rooms: Most-starred talks in biggest rooms
For example: Talk S08 has “50” likes
Room 8’s capacity is 1000 seats