Every story has one; a timeline. That ticking clock might be at the front of your plot, akin to a ticking bomb. Or it might be a passive passenger on the journey; slow, steady, but relatively quiet.
Every writer has the nightmare of discovering that they've written a passage where Monday happens twice or people are getting ready for bed on one page and eating dinner two pages later. But the passage of time can add a new level to your storytelling as your characters become more and more aware of the sand slipping through the hourglass and their goals are still tantalizingly out of reach.
Fiction, of course, allows us to play with time - to make our characters lives far more event-filled than our own. I doubt that the majority of real-life detectives solve their cases within a few days of getting the call to the crime scene. Most singletons don't spend their daytime at fascinating jobs surrounded by quirky co-workers and their evenings either on dates or with their closest friends in wine bars or quaint apartments with hard wood floors and high ceilings. Let's face it; most coupled-up people don't spend their lives life that either.
Stories are an escape - a world where bigger things happen faster than in real life. Give your readers a ride.
Just remember, a ticking clock always comes in handy; even if it's only a reminder that your MC forgot to take dinner out of the oven.