You're on balance at the back of the court playing level doubles, partner at the net. Do you choose to smash down the middle most of the time to cut down the angle of return hoping your partner can get on top of a weak reply, or do you smash straight (e.g. at defenders hip) as it's the shortest route down?
I guess you could smash down the middle since, if its a weak return, your partner could dominate on that. But if its a good clear back to you, you could also get it. So you might as well take your chances and see what happens. However, I think if you smash straight at the defender, you might be able to end the rally there. I think either scenario would be suitable, it just depends on your opponents.
going down the middle is generally perfered in doubles. As you mentioned it yrself. it cut down the return angle and give the front person better chance of interception Plus it offers the chance for the other side to get confused as in who should get it. Of course if there is a clear opening or the other team is clearly off balance, u don't always have to smash down the middle. Espeically if there is a weaker defender on the other team then i would mostly go for the body instead.
smashing down the middle is the most orthodox shot b/c there is less pressure on you than if you smash cross court and they drive the shuttle back. Orthodox is not always the best though b/c ppl are expecting it so occsionally cross courts are good as well as straight at your opponent. Smashing straight at your opponent if your partner is strong at the net is very effective.