I think if I ever went “treasure hunting”, I would try river panning/prospecting before metal detecting.
At least, if you go to the right rivers, you are pretty much guaranteed to find something. Unless you’re lucky, it won’t be enough gold to cover your time & trouble, but you still won’t end up empty handed, and who knows? There are “glory holes” out there to this day that nobody has found yet, guaranteed.
I have no idea why but I have read that nearly all ancient swords that are found, turn up in rivers.
I think one reason I did not find more treasure was that I was just beginning to get arthritis. I didn’t even know that is what was causing me to ache so much back then but after treasure hunting for an hour, I would sure be hurting.