The NBA just did this in their lead-up to the bubble (in-market testing, in-market individual workouts, in-market team workouts, bubble arrival, entry quarantine, team-isolated training camps, teams playing against each other) and it worked very well. If you just jump into full team practices, then everyone is exposed when you find out one member of the training staff picked it up from a family member. The slow lead-up allows you to limit the scope of contact of that one potential person. A couple of teams have already had cases and frozen workouts, and the slow lead-up means once they’ve contact traced and quarantined they will have severely reduced the impact.