No matter how well portable buildings are constructed, dragging them around involves a lot of strain and wear which considerably shortens building life. Especially where a portable building must be moved over graveled roads or sandy soils, rapid runner wear means expensive maintenance. And since the runners make up a part of the actual house framing, replacement is difficult.
Armstrong, Ray E.
"Stop Dragging Those Hog Houses,"
Iowa Farm Science: Vol. 8
, Article 5.
Available at: https://lib.dr.iastate.edu/farmscience/vol8/iss7/5