I started in about 1976-ish (as a pimple-faced Jr. High kid). And I can tell you : It was not "gold rings and silver coins, hand-over-fist" easy.
Perhaps I was in an area that , even then, had competition. We just hit the *obvious* spots like schools yards and parks. And without discrimination (using 77b's and 66TRs), we were at the mercy of pulltabs, foil, and 5" depth @ tops. On a typical "good" day at the school, we might come back with a merc, a silver washington, and a few wheaties. So it was NOT "hand-over-fist" easy pickens, even then.
It was actually faster and better when disc. came out (TR disc. first, then motion disc. with the 6000d made it even better). That was in about 1980.
The fabled stories of handfuls of gold rings, or handfuls of silver, were NOT the "common story" in the 1960s and '70s. Those stories were exceptions. Like divers being the first ones to ever fan the sand beneath water slides @ still-water lakes (or still-harbors, etc...). Or the first persons to ever hunt underneath the tilt-a-whirl rides (that turn you upside down so all your coins fall out of the ride). Or the first persons to ever hunt at the foot of concession stands set on sand, etc..... Or someone working phenomenal beach storm erosion days (like the 1977 storms, or the '82-'83 storms, etc....). Which could be repeated if and when mother nature gets off her duff, at any time.
Remember: The machines were primitive in those days. I actually get older coins and do better these days.