I agree with Barb: Hard Deadlines, for projects, for milestones etc belong in the calendar. Of course it is vital to use the system once it is set up! Check the Calendar in the morning.Cpu_Modern, could you explain further how you use the tickler for this?
The Tickler is good to manage the softer urgencies, so to speak.
Let's say for example I want to get the lawn mown very, very soon, preferably the next day the weather is appropriate to do it. I will then put a note in the Tickler "Lawn? Weather?" for the next day. The next morning when I process the Tickler I get that note look out of the window and see: nope, the weather is bad and put the note back into the Tickler for the next day. I do so until I catch a day with good weather on that day I'll mow the lawn.
This way the "Lawn? Weather?" - note doesn't clutter up neither my NA lists nor my Calendar. It makes sense to put it in the Tickler, since the best way is to look only once per day on that item.