I have a friend who left on a major road trip at 7:30pm when he wanted to leave at 5:00. He got involved in a project that he needed to finish which resulted in his delayed departure.
I have no doubt that if he had a plane ticket for 3:00pm, he would have been in his seat. All those things he “had” to do suddenly wouldn’t have seemed as important. We’ve all been there.
Driving and flying represent two different kinds of deadlines – soft and firm. If you set for yourself a target where it doesn’t really matter if you hit it or not, it’s best to use language that indicates it’s not a hard stop. If you set “deadlines” that you repeatedly ignore, over time your brain (or your staff) registers that “deadline” means more of a “wish” than a hard endpoint.
Both kinds of deadlines have their place. Be clear on which one you are imposing.