Slack. People do not learn well when they are preoccupied, anxious, or hurried. If team members are thrashing about trying to figure out just what it is that they are supposed to do, or if they are in a headlong rush to get their work done on time, it is doubtful that they will make much headway in building their individual or collective knowledge and skill.

Team learning requires, at minimum, some protected time and at least a moderate level of collective safety, conditions that are hard to create when members are right in the middle of task execution.

via J. Richard Hackman