I think people get confused sometimes that they have to pay the total interest. Nearly all mortgages in the US are simple interest loans. Interest is only paid as long as the loan balance is outstanding.
If the rates between the 10/15/20/30 are roughly the same, then the person should take the 30 and pay it back like they would the 15 (~double payments). The reason is the person is now protecting themselves from life change risk. If they lose their job they could go back to making the minimum payment.
If the rates between the 10/15/20/30 are roughly the same, then the person should take the 30 and pay it back like they would the 15 (~double payments). The reason is the person is now protecting themselves from life change risk. If they lose their job they could go back to making the minimum payment.