I agree that a professional can do these things.
Nonetheless, when I message a cute, young guy who lacks any business savvy he’ll not have thought about this. He simply picks a number that seems right and sticks with it. So, I hear things like “yes, the second and third hours are also $300 each”.
I’m not going to presume to give anyone a microeconomics lesson via text so it becomes a lose-lose. (Assuming he is savvy, has thought about it and still stuck to his above-the-norm rate.)