A weekly planning session takes 20 to 30 minutes and has five parts: clear the inputs, review last week, choose three outcomes, place the work on specific days, and pre-decide what gets dropped when the week goes sideways. That last part is the one almost everyone...
To use a digital planner on a tablet, you import a hyperlinked PDF into an annotation app like GoodNotes, Notability or Noteshelf, open it in a notebook of its own, and write on the pages with a stylus or type into them with the keyboard. That is the whole mechanism....