Focus on grouping filter categories?
 

Focussing on projects or folders is a great feature in OmniFocus.

But why the focus functionality is restricted to projects and folders in the planning mode? Why not extend the focus command to the categories created by the grouping filter?

I think that would be very helpful in planning as well as in context mode:
When doing my daily review I want to see only those projects I want to review daily. So, with an extended focus functionality I could set the grouping filter to "Next Review", focus on "Today" and ten save this as a perspective which really shows only today's reviews.

In an analogous way in context mode I could focus on tasks which are due 'Tomorrow' , 'Within the next 3 days' or to overdue tasks and then create the corresponding perspectives.