The card view in planner is a powerful tool, but the horizontal-only layout of the buckets extends far out and becomes hard to manage with a large number of buckets.

With "stacks", you can group a bunch of buckets together and still have the vertical list of tasks, but be able to collapse a "stack" and open a different "stack", or open multiple "stacks" at once to get a project overview. Each bucket will still be scrollable, as would the entire window of stacks.

This would give project managers a much more comprehensive overview of a project and make navigation a lot easier and more intuitive. It would also add another layer of organization which can aid sorting, filtering,

In Stack>Bucket>Task format, For a territorial sales system it could be Territory>Market>Target (Southeast, Atlanta, TNT network). For a Departmental layout it could be Department>Objective>Task. There are may ways this could enhance the tool's leverage for large scale organizations, projects, etc.