Life rarely perfectly follows a plan. But that doesn't mean that you should just give up and not make a plan. It means that you should embrace a realistic expectation of what planning can and can not do for you.
What you're really doing when you think you're multitasking is shifting your attention from one thing to another at an astonishing pace. While it's fascinating we have this capability, it's not exactly the best use of our mental faculties.
The truth is, I already knew I was going to be late and instead of just owning it, the part of my brain that wants to pretend I'm powerless takes over and starts inventing reasoning to take away the supposed sting of personal responsibility.
Your relationship to time is one of your most important relationships. Consider that time is the currency of your life. All the choices you make about how to spend your time add up to the kind of life you have.