I'm thinking about using knife hinges on a project that involves a pair of inset doors. I found a nice FWW video on a router jig for cutting the insets for the hinges, which emphasized a consistent gap between the doors and the frames that is dictated by the distance between the upper and lower "knife." That all made sense, and the door he used in the demo seemed to open fine, but... I am wondering whether people have had issues with the door binding against the frame with such a small gap, and whether the edge of the door typically needs to be relieved or back cut to open smoothly. Seems like even more of an issue with double doors. Am I overthinking this?
Addenda--also, I can't seem to find any rules or thumb or specs on how you size knife hinges for door. Is "as big as you can" the right metric?