I can see where the OP is coming from in relation to expiring miles that he/she has earned due to work

however the reality is that if he/she is flying and earning the Avios are valid indefinitely as long as they have flown within x period, is it still 3 years ?

even if they aren’t flying at all to earn, spending within that period also keeps the account active, but there are vast amounts of easy and cheap ways to keep your Avios account active and not loose the miles including a simple £2.50 transfer of Tesco points once every x years

cs