It has been suggested that one should only play prizes on the offensive or defensiive side until your achieve the big payout.

Anyone have factual information on this?

No I've never found this to be true I do work more off then def and payouts for me just are garbage no matter which I do.  Maybe someone else who has better luck can tell you.

It all depends on the payout your looking to get. But also on how much you owe to the bank. If you owe too much then and you want a defensive payout do offense until you're confident you're ready for a payout. Then switch back. What I do is I widdle down a defense prize till the lantern is yellow stop and do offense prizes then switch back when I think its time for a payout. Reason being is offense always has a higher value than defense. 

bank = resource value of troops in payout, resources gained +12%

paying back bank = resource value of troops sent to prizes.

The downside to doing just offense or defense prizes is you end up with too many of one kind of prize. As you go thru the levels all your low level prizes will be the opposite of what you're doing (off or def). This may not seem like a problem at first but when you have trouble getting back up to higher level prizes you're only option is the opposite of what you were doing. If you are going the def route you can always throw offense at defense prizes to pay the bank back faster