As a former executive, and now executive advisor, the best productivity "technology" is combining a physical At-A-Glance planner with the alarm app on your smart phone.
I learned about the advantages of a physical planner from my mentor, famed consultant Alan Weiss.
With a physical planner (paperclipped to the correct month), you can pull it out, click open your pen, and schedule an appointment faster than the other person can open their on-line organizer!
Then, each evening, you set alarms (15-20 minutes ahead) in your alarm app corresponding to the entries in your planner. So, when your alarm rings, you check your planner and know what to do next.