I know quite a few beaches around here that you'd be lucky to find a bottle cap at - They are pounded to death daily by locals.
I have even been driven back onto the sand in some locations, with some success.
I don't get discouraged, I keep looking as there are bound to be something they missed or very recent drops, its fun trying anyhow.
There is this one beach I used to do great at, they don't allow detecting between memorial day and labor day, the day after labor day its open season there.
3 years ago it was just me and 2 other guys, found i gold ring, a silver bracelet and 2 stainless rings. Next year I missed, last year I got there about the crack of dawn, still dark.
I was amazed to see about 25 guys out in the water, some with flashlights on their heads. I went out and found 2 rings anyhow.
This year, just last week in fact, I went back and there was about 8 guys out there and a couple combing the sand.
Didn't stay long, my wetsuit leaked and it was cold, detector started falsing so this year there was a bust.
I ordered another wetsuit so hopefully will be back out in the water soon with less competition, to see what they missed.
I think the reasons for increase in people detecting beaches is 2 fold -
* AT Pro, before that you'd have to spend $1K+ to get in the water, now you can do it for half of that.
* Youtube videos exploding with beach detecting, many people watch and think hey, I'd like to do that, so they do.