If you have a ready-made template, it's quick to apply it and change it.
Or if you have a good idea of what you want to do and are comfortable with the layout, it won't take many days.
But in fact you do out, the other party is not satisfied, and will keep asking you to change. Especially if the other side does not understand, it will be even worse. Designers need to have their own opinions, and I've suffered from this before.
It was clear that what I started to row was correct. But he asked me to rearrange it according to his requirements. At that time, he was so sure that I was helpless to listen to him. In the end, it dragged on for months before he suddenly sighed and said he didn't understand. So I had to line everything up from scratch again. That was kind of a lesson learned.
That said, that picture book, that's 12 pages. It took months of grinding to get that money.