Recovery time from being Downed

What determines how long it takes a character to go from being Downed to recovering real health?

For all 1* characters it seemed to be 2-3 minutes.

For 2* characters I’ve seen anything from a couple minutes to an hour (Captain America).

For 3* characters it seems to be mostly around 50 minutes, but IM40 is a full 45 minutes shorter.

Seems character dependant. That’s one reason why I love Daken. Woukd be interesting to record health recovery speed for all characters.

Pretty sure all but 3 are 12 hp per minute. The other 3 are 24.