It is sometimes easy to make the mistake of putting something into OmniFocus when it should be in the calendar.
http://www.asianefficiency.com/sched...th-each-other/
OmniFocus is a task management tool, not a time management tool. Time management is a fallacy because we cannot manage time. Time will go on about its business regardless of what we are doing. However, we can manage tasks and be able to do tasks in a set time.
I use OmniFocus together with a calendar (such as iCal or BusyCal).