How does resource surveyor actually work?

I get the general idea, search and go to collect. But for example, I’m looking for toenails, and there are plenty around. I know I just picked up the ones in ashtray, black widow nest and pipe in upper grasslands before they respawn so I travel to the ones in lower grasslands. There’s nothing there.

Is it not pinpointing the exact place of a resource? I understand animal parts cannot be on exact spot as they move around but toenails? What am I missing here?