First question is where do you accrue your miles to ?

SQ, TG or A3 ?

Flying J class on say Air China will net you 125% / 125% / 200% of the miles flown.

Say you fly J on BKK-PEK-SZX return, thats US$1,666.45 for 6538 BIS miles = > 8172.5 / 8172.5 / 13076 miles when credit to SQ / TG / A3. Not 17K but you get the idea.