I'm currently illustrating a children's book. I mean, I'm a full time student, so that takes a lot of time away, but dear Lord....it takes a lot of work. There's a ton of planing, character development, proofing, then the sketching, inking, and painting. You also have to do color planning and stuff. Oh, and lettering. I started the project in the beginning of the summer and I'll be shocked if I finish it by May.
When you draw your own book you don't have to e-mail anyone and ask "is this what you were looking for?", wait for an answer, and then possbily re-do all the parts they didn't like. Half the work of doing something for somebody else is communication and administrative work. The last illustration I did, and it was just ONE illustration, now has an e-mail trail of like... 30 e-mails. The illustration itself only took about 11 hours of drawing, but about 2 weeks passed in realtime from "Hey we want you to do a thing" to "Thanks for the final picture!" Multiply by 32 and you have spent 64 weeks on a picture book. You can probably compress some of that because you don't need to sign 32 contracts for one book, so that easily brings you down to about a year.
Fair enough, though I've heard the same thing from people who do write and illustrate their own books. Though I'm not sure I've ever heard it from someone who self-publishes, so that may have something to do with it.
The publishing process for a book takes about a year regardless of how much actual work the artist is doing on that one project. Very few people spend 8 hours a day every day on writing and drawing the same thing. There are some artists who work very quickly, though, and some that work very slowly.
The other thing is that most of us are terrible procrastinators.
Can't argue with that last one. My first book took only a week to get written, illustrated and published. My second book took all summer and then some purely because of all the time I spent procrastinating on it
Well, I would hardly think that Jumanji or Where the Wild Things Are are made up of illustrations that took only a couple hours a piece. I suppose it depends on how much time the artist devotes to his craft.
Part of it is because of the amount of planning that goes into it. Just because the book takes a year doesn't mean the artist has been drawing every single day for that year. They had to pitch character designs, do concept pages, make the illustrations, adjust the illustrations repeatedly, etc. It takes a lot of work to get to that finished product. There's also the fact that, especially for writers illustrating their own work, they have a ton of other work to do as well. They may be writing other works, illustrating other projects, doing book tours, etc.