Dude, you are utterly mistaken. The vast majority of experienced players whether here or at flyertalk advocate redeeming for J/F only.
A few newcomers have recently suggested that Y redemptions might be viable, and others are helpfully nudging them away (to either use a cashback card instead, or to hold back and redeem the miles for a premium class). This is not a system which you can game using your "gut feel" - you really need to take out your calculator and crunch cold, hard numbers.
Of course we can sit back and say "to each his own", and of course every one has a right to spend their miles however they want, with or without prudence - but being a platform for sharing, I am just trying to dissuade people from making the same mistakes I used to make when I was much newer to this game. I still feel like kicking myself in the face for all the tens of thousands of miles I spent redeeming Y flights a long time ago... and back then, to think I was patting myself on the back for getting all these free flights.
