I understand totally the cautionary attitude, but after having set up really thousands of instruments, I never had a single problem with even two complete turns of the nut of a truss rod (tensioning it, not releasing the tension, of course).
But, as there's always a but, I always sense the pressure and tension when doing this. If it becomes hard or starts making weird noises, I always stop and if it's a single action truss rod, before any attempt, I always put some graphite grease on the thread.
That said, I've seen a luthier breaking a trussrod before my eyes by applying too much strength when it became harder to turn. Sh*t happens.
In fact the truss rod almost always breaks at the thread, which is the most fragile place.