Re: Day planner. On paper.
I'd love to have hung on to my Filofax diary but once shared calendars hit the company system, paper diaries were doomed. It suddenly became much easier for those without secretaries to plan meetings and make sure people could attend. I don't conflate "easier" with "better", BTW. In the final years of my life at a big company the number of meetings was really starting to impact performance. I'm sure a return to paper diaries would have made work better by reducing the number of pointless meetings.
I still use my Filofax for notes, jotting down ideas, shopping lists and stuffing random bits of paper into to be read later. It's much more satisfying to cross out a ToDo on paper than it is to hit a check-box on the screen.