Let me give you a real live example of something very recent. My daughter is an AEA stage manager who was scheduled to PSM Time Stands Still. Unfortunately, two weeks before rehearsals were to start, she was struck by a drunk driver and broke her right knee and her left ankle (she had been on a bike), and her right leg was encased in a full leg immobilizer, exactly like the lead in the play. Though she was out until previews started, and then came back, she did come in to a few of the early rehearsals, in her wheelchair, just to see how things were going. So, the first time she came in, the director asked her to sit down with himself and the entire cast and describe what her life was like under these circumstances. And they spent a full hour of rehearsal time doing it.
CZJ at opening night party for A Little Night Music, Dec 13, 2009.