The current design of Plan feature on mobile (both iOS and android) is (to be very honest) a failure. Here's a quick summary of my thoughts:

- You have to go through all the Today tasks in order to reach Next tasks. In many cases, all you want to do is to pick tasks in Next or a specific project folder to Today. Then you're out of luck. You have to flip through all the Today tasks (however much it is) in order to reach the Next tasks.
The project applies a very unnecessarily inflexible planning flow.

- Inconsistency in the user interface: today tasks are in flipping mode, while next tasks are in list views.

- Plan feature offers the ONLY way to slide through all tasks. The normal task view doesn't allow the user to do this.

Suggestion:
It would take a much longer post to propose a re-design of the planning system. However, I'd simply point out what the older iOS version of doit.im has already achieved (though with lots of bugs in various scenarios): Offer slide gesture support so users can flip through all the tasks and highlight (using the star that's right below the task view). It's much more flexible and in my view offers a far better experience than the rigid Plan feature.