that's only correct if you assume everyone starts afresh every time they move - eg start with a 25 year mortgage, move after 5 years, take out a new 25 year mor

that's only correct if you assume everyone starts afresh every time they move - eg start with a 25 year mortgage, move after 5 years, take out a new 25 year mortgage. why wouldn't the next mortgage be a 20 year term? that's a like for like replacement at that point.