There was a particular beach in my area awhile back, that got beat up and eroded out with storms/waves. All the light stuff (tabs, foil, caps AND EVEN ZINC PENNIES [d/t they are lighter coins]) got washed out ! Not many old silver coins though. And to the extent some silver coins were there, they were salt-water black "toast". Hence old coins nor clad was our objective. Naturally we were all wanting gold rings (who wouldn't?")
The first day or so, we ended up with 250 or more coins each. Essentially as fast as you could dig. And perhaps 1 to 2 gold rings each. Hence about 100 to 1 ratio on gold rings versus coins. And when I got home from that first night, and put all the targets out on the table to count, out of the 250-ish coins, clearly 80 or so were copper pennies. Wohhooo. Another 80 or so were copper dimes. Wooohoo. And then quarters, nickels, fishing sinkers, car keys, etc.....
The next day I wised up and start passing copper pennies and up. But accepted zinc penny (since there WERE no zinc pennies there) and downwards. An occasional dime or penny would still read in, because it was thinner on account of beach-tumble effect. But for the most part, the coin counts dropped dramatically, as I was passing most all copper pennies and quarters. And the nickel count went up from a previous count of 25 or 30-ish, to 80 to 100-ish ! And instead of ~ 2 gold rings, now the counts were 5 to 7 gold rings. EVEN THE BIG MEN'S GOLD RINGS were not missed, since we had edited in zinc.
This was a case where it was going to be simply impossible to strip-mine every signal out. Within 5 days it was sanding back in, and at no time, in any of the day's tide cycles, could you ever exhaust the signals. Nor even find the end of the pocket's length on the beach! And by the 6th day, it had sanded back in. And will probably remain so for the next 20 or 30 yrs. before it's ever that low/eroded there again.
So in that case, you can see that it is in fact very wise to cherry pick, to "up your odds" at gold ring. That is, unless, you are turned on by modern copper clad pennies and dimes and quarters.