Hagen farm name

I have so far learned if Ole G Hagen's father was Gunder he would be Gunderson. We know he took a farm name for his American name so he is Ole or Olaf Gunderson, born June 7 1870 in Laurdal, Telemark. What neighboring areas would have a Hagen farm where he might have lived before he came to Wisconsin in 1886? His father was Gunder and his mother Kristi but no family name. The closest I have come to the Gunder and Kristi is Aslakson in Mo parish in 1865 census. Did farmers move from farm to farm as the work demanded? Do parishes cover more than one farm or even cross county territories? Lost in the Hinterland, Elaine