Actually, the wax pencil/crayon trick really doesn't do anything.

If anything It's NOT a good idea.

Look at it this way. A CA hinge is a plastic ribbon with a fibrous coating on both sides. When you add CA, it wicks its way into the fibers.

When you draw a wax line on it, that line sits on top of the fibers - so the CA will still wick under it, but now you have created a barrier on top where CA can "pool" because it can't wick into the fibers like it's supposed to.