I was wondering the same.
There might be some survey marks already placed. I own a couple different pieces of land and if I walked them one could find the old survey marks. Sometimes this is just a metal rod sticking out of the ground or possibly even a tree that is marked.
Yes, I have found three of the four corners.(including our shared ones.) But he still thinks he owns more so i gave to get it surveyed. This piece of land hasn't been surveyed since 1920.😁😁