Craig and James,
Absolutely! Loose coupling bolts can do the same thing. I should have thought of that!
I'll add two more things to the excellent list of solutions that James posted: A second "jam" nut works well--if there is room. I have also taken a punch to the threads where they disappear into the nut. This doesn't work with nylock nuts, but with regular nuts and lockwashers it adds a significant extra measure of security.
On my old boat the bolts actually threaded into the prop shaft flange, so no nuts. The bolt heads were drilled across the flats, and then wired to prevent backing out.
Nothing replaces checking on a regular basis.
In addition to drive train fasteners, the others I have had chronic problems with on every boat have been in the steering system. The irregular, reversing, loads make it tough to keep everything tight. Again, nothing is more important than checking regularly.
Annapolis, MD, USA