Identifying things on your list for today that will take significant time to complete is helpful. You might want to block off time for these longer actions. The BIG Rocks perspective is the same as the Today perspective except that it only shows actions with an estimated duration of more than 30 minutes.
Please Note: For this to work as expected, the “Tagged with any of” rule must be updated to reflect your “today” tag.
If you’re using OmniFocus 4.7 or later, you can also use the On Deck: BIG Rocks perspective.

