Sketching artists often use a grid of squares to get their proportions right.
Once the sketch is made, the grid is often erased away. It is merely something that exists in transition to help the artist with the proportions of their drawing. With practice, the artist learns to draw without a grid. By then, the grid is integrated into their being.
A schedule works in a manner similar to that grid. Each hour breaks our day up into 24 uniform chunks. A schedule helps us sketch out our day. Its absence could easily skew our day out of proportion.
With practice, we learn to discard our schedule and live from hour to hour. But then, the schedule is integrated into our being.