How do you know you’re misusing due dates in your task management app? You’re setting due dates that are I wan to do by dates but that have no externally corresponding due date. In English: you’re assigning due dates to tasks that aren’t actually hard deadlines.
And a good sign that you’re doing that is you find yourself looking over your "Today" list and moving the date to the next day. Again. And again.
What’s wrong with this?
Nothing, really. But ultimately, due dates are when something is actually due. It’s a deadline.
"But I set a deadline for myself!" you might object.
Don’t do that.
Simpler task managers don’t offer many ways to bubble a task up to your awareness outside of due dates. But apps with more robust metadata, like Todoist and OmniFocus, to name a couple, can help you focus your attention on urgent and important tasks, while not tricking yourself with due dates.
My current example: I wrote about applying the Eisenhower Matrix to Todoist here on Uncorrected a while back. My particular system is a mashup of GTD and this method. Besides organizing tasks into projects with corresponding tags (context, in GTD parlance), I apply a P1 tag to things that are urgent and important (things I should do as soon as possible), P2 to things that are urgent but not important (things i have to plan), and important but not urgent (P3, not important but urgent), and can be delegated.
That organization scheme adds another processing step when getting things out of your inbox, so there’s some friction there. But it helps you focus when you find your "Today" perspective full of things you can keep pushing off to tomorrow. Working out of your P1 or Important/Urgent perspective keeps you moving forward, while things that are actually due today can appear in Today.