RE: Is it really necessary to pin nylon or CA hinges?
I always pin any strip material hinge.
My old club in the UK would not alow a model to fly with unpinned hinges.
I use 'furry' mylar hinges and always drill from the bottom through the hinge and wick in thin CA through the drilled hole. Then it is a matter of seconds to snip the point off a cocktail stick, add a lttle thick CA or epoxy and push it in. You quickly get the feel for the depth. Snip off the excess when set and you have insurance.