R' Chaim Tzvi Teitelbaum (1879–1926) related that someone once came to the Noam Elimelech and showed him his schedule in which he had written what he would learn at any given time. The Rebbe showed his approval but not before he wrote after each plan ופעמים להיפך — sometimes the opposite. There is a saying, “Planning is important but the most important part of every plan is to plan on the plan not going according to plan.”
We say in Maariv מחליף את הזמנים ומסדר, changes the seasons... We can understand this in a different way: Sometimes we are unable to keep our regular schedule. It can be because of a doctor’s appointment, taking care of a child, sickness or something else. Nevertheless, it should be with order. Plan the day before! This is how we can interpret מחליף את הזמנים — at times we need to change and adjust our schedule. Still, it should be organized — ומסדר.
It has been said that there are two types of people who fail: People who don’t have a plan and people who stick to their plan. One must be flexible in life and roll with the curveballs.
The saying goes, “Write out the future, but in pencil.”