Adjusting is normal, expected, and encouraged. It means you’re setting a plan, then adjusting that plan as new information arrives. — You Need a Budget: Rule One

This is from a budgeting methodology. However, this also applies to planning in general.

Things rarely go according to plan. But that doesn’t mean planning is useless. Planning gives you enough insight to know what to anticipate. What was planned isn’t absolute. It can and should be adjusted as events unfolds.