Not everyone uses a paper planner and sometimes you don’t have a pen or piece of paper near by. Don’t let that really important thing slip from your mind. Often times you have your phone close by so you use it to record the thing that you just remembered that you don’t want to forget. iPhones have a great option to set a reminder for a set day/time or when you arrive at a location. I use this all the time. I also have it written down to check my reminders when I complete my weekly review so I can move any items that didn’t get completed in to my paper planner. The key is to put the information somewhere besides your brain so you don’t clutter your bandwidth with minimal information and using reminders on your phone is a great way to do this.