(if you do plan well)

In what ways was this lesson presention better than the previous one? What did the teacher do right this time?

Lessons that are well planned are more likely to help students and teachers...

Lesson planning also allows the teacher to visualize (and, therefore, better prepare for) every step of the teaching process in advance. This visualization typically increases teacher success.

A well done lesson plan can also "save" your class if for some reason you can't be there to teach. The lesson plan will provide invaluable guidance for the substitute teacher.

Lesson plans also provide a record that allows good, reflective teachers to go back, analyze their own teaching (what went well, what didn't), and then improve on it in the future.

In addition, this record will save you time in the future. When you teach similar lessons you can refer back to your old lesson plan (kept on file) and "recycle" the successful elements (instead of starting "from scratch").

In sum...

...although it requires an investment of time and energy, lesson planning produces many valuable benefits.

Don't you think it's worth it?