Ayup. And also knowing that lowering the risk of a group might very well increase the risk for someone.

Like the examination that I'm going to go to next week with 38 people that cannot be rescheduled or moved without a lot of hassle (including disruption of staffing for the local hospitals next summer). To minimise risks we do it in three rooms rather than two. Each room will be slightly safer (due to less people in it), but we will expose one other person to a higher risk (the additional exam assistant).