I visited lots of cemeteries and soon found that some of my pioneer ancestors didn't have gravestones. Or maybe no stonecutter lived in the area. The family could identify the graves, until the last of a generation died. When I visit an old country graveyard, I wear boots. The poison ivy may be knee-high or the grass wet.
Winter is a good time to visit.
Remember when an old stone is copied, weathering may make the 1s 4s 7s look alike, also the 3s 5s 8s. Be wary of dates in published books. In one case, I found that when a stone was put up long after a man's death, his death date was set 10 years too early. And don't visit a country cemetery after dark with a flashlight. After I have quite a bit of good data on a family, I publish it, putting copies in libraries and a notice in the Genealogical Helper.