Unpublished procedures are used in numerous places I can think of and have been used safely by some pilots for decades
The thing that few admit or of course they were visual
This isn't a statement on whether they should be done or not just an ackowlegemrnt that they are
Just because it published that makes it safe
If it's not published it's not safe ?
One recommendation above is letting down at an airport with a published procedure and going to your destination below
The most dangerous procedure is low level scud running with low cloud and poor visibility
I can remember decades back flying to Caernarfon it was common practice to cross the mountains in IMC fly over the NDB and then let down over the sea I suppose that's a non published procedure
I am sure we would all love to Lock onto a nice ILS but sadly smaller airfields are not so equipt! The have to fly brigade concoct all manner of solutions and always have For as long as I can remember
So it's probably something publicly shunned but privately ??