Writer Shawn Blanc on smart custom perspectives in Omnifocus:
In short, you should create your own custom perspective for “Today”. And let that list show you all the tasks which are either Due today or which are Flagged. When you are doing your daily review and scrubbing your list, don’t think about what’s due — because it should already be given a proper due date — instead, just flag the tasks you want to get done that day. Then, go to your Today perspective and now you’ve got a list of items which are both urgent (i.e. due today) and important (i.e. flagged).
Bingo. When I started using Omnifocus, virtually everything had a strict due date, which became maddening after time. When everything is “due”, it’s hard to manage what is really important. Overall, be less aggressive with real due dates unless it’s really due.