Once my character got to the corner of my land survey it kept digging forever, but it wasn't losing stamina nor was it actually digging any dirt up.
It just stood there in the digging animation until i moved him. I managed to do it multiple times in the same corner too. I also checked to see if the tile was dig-able still and i was able to dig it manually, but the incline was pretty steep if it's different for land survey.
If it makes a difference I've only had this happen with land surveys that were overlapped to form a conveyor belt.