It takes a lot of thinking about.

I don't know how grown-ups manage to write all they do.

It must make their heads ache, especially lesson books.
Albert-next-door only wrote one chapter of the serial story, but he could have done some more if he had wanted to.

He could not write out any of the things because he cannot spell.

He says he can, but it takes him such a long time he might just as well not be able.