More sensitive resource layers display option

For those of us who are perfectionists about picking up all the ore, it can be annoying to have to either look over a suspicious area with a fine tooth comb or dig much more than necessary. I'm not sure exactly what the resource overlay is notifying us of—a majority of one layer of a given 2x2 or 3x3 area is X?—but if whatever triggers the overlay to show up could be adjustable to trigger on ANY amount being present, I think that would help those of us who want to get it all have peace of mind. Ideally, however, it would be toggleable back to what it is now for people who don't mind leaving a scrap here and there if it saves a lot of effort.