In this new article — To get stuff done with OmniFocus, take it easy on the due dates — Peter Akkies talks about using due dates not for intentions but for consequences.
Don’t give everything a due date, in other words. Even if you intend to get it done on such-and-such a day. Even if you’re quite sure you’re going to get it done, because you really mean to get it done that day.
Instead, use due dates for when the consequences matter — for when you’d lose a bid, alienate a partner, miss out on a life-changing deal.
For things you merely intend to get done, or when the consequences aren’t so dire, use other methods such as tags (especially the Forecast tag, if you have the Pro edition).