I always used a level 2 doctor. However, I got two players injured on 18 Feb 2014. As a result, I recruited a level 4 doctor on 19 Feb 2014.
As one of the player injured for 2 weeks (i.e. 14~20 days to recover), and updated to "injured for 1 week"(i.e. 1~13 days to recover) on 24 Feb 2014. He fully recovered today (2 Mar 2014).
As a result, level 4 doctor speed up the recovery process, from 13 days to 6 days.
Let me know if there is any thread for the research of doctors at different level, or could anyone of you share the experience of doctors, please?
HAHA