How often do you use/need a 50 amp to 30 amp adapter?

In four years I have never found a 50 amp only post. I have had occasions to use my 15 amp adapter but never needed a 30 to 50 amp adapter.

As matter of fact, in the last four years and 30,000 miles of towing, I have not even found a cross wire circuit box. I have a circuit tester and surge protector. Perhaps because we almost always stop at a State Park, the chance of a miss wire is less probable. Still it is always a good idea to check.