Thiel migrated away from direct wood fastening to inserts sometime after I left. There are advantages of reliability over multiple uses. However, metal on metal under vibration will (reliably?) vibrate loose. Breakaway Locktite helps as does Mortite onto the threads. But over the years, inserted fasteners seem to come loose and direct to wood fasteners seem to remain tight. I'm going with plan A and use direct fastening. Of course castings need inserts. Brass is a good solution, or other non-magnetic substances - non-conductive is even better, since electrical fields are affected by any conductive material, magnetic or not.