Two delusions we suffer from

Both things we desperately want to believe. We tell them to our colleagues.
The first may also be told by department chairs to try and persuade someone to teach a course.
The second we may tell prospective students.

1.
Teaching this course for the first time won't really take that much time.
I won't be a perfectionist. I will cut corners. After all, I have someone else's notes (and assignments, exams, ...). It is a really good textbook....

2.
My student can complete their Ph.D in the minimum amount of time [3 years in Australia].
They will work really hard. They are smart. They will cut corners. I will supervise them closely. The project is quite straight-forward. I won't repeat past mistakes...

Face it. Neither is true.
Or do you believe them?
Why or why not?