Originally Posted by
Sannomiya
For example, booking round trip flights a week or two before the earliest expiring miles expire, resulting in an award round trip flight that could be as far as almost 4 years after the first miles-earning flight.
Actually if you make the reservation after the Amadues switch, you can book at ticket 330 days out and that ticket will be valid for 1 year from the date of your first sector
https://www.jal.co.jp/en/info/pss/jmb/inter.html#AC_TSF
So you can keep your miles valid for almost 5 years