collagenase for healed burns?

I took care of a gentleman with some recent but healed facial burns (burns were about a month old.) Even though I don't know anything about burn care, I was hesitant to use the collagenase that they had written for. My understanding is that it's an enzymatic debridement, but this guy's burns were perfectly pink with no eschar, and were on the way to being well-healed. My question is, how long do you use collagenase for, normally?