Sorry, don't mean to step in on this thread, but I have a question that perhaps might be relevant here.
I have a number of books I purchased back years ago on nugget shooting, that mostly cover the desert Southwest including Arizona and southern California. One in particular by Pieter Heydelaar (Successful Nugget Hunting Vol. I), written in 1991, lists many locations. He also wrote a Part III which exclusively deals with the above-mentioned locations.
Of course these books contain important techniques and discussions on geology which are always important, but should one consider the locations worked out by now? OK, so there may be a stray "gram-mer" here and there, as it's impossible to completely clean out a location, but are the days described in these books where desert nuggets were reasonably plentiful (using old VLF technology to boot) considered over? The photos in these books are nothing short of astonishing.