“The second tactic that helps is the use of overflow conditional blocks. If you’re not sure how long a given activity might take, block off the expected time, then follow this with an additional block that has a split purpose. If you need more time for the preceding activity, use this additional block to keep working on it. If you finish the activity on time, however, have an alternate use already assigned for the extra block (for example, some nonurgent tasks). This allows unpredictability in your day without requiring you to keep changing your schedule on paper.”