Your answer to that last question made it sound sort of like it's typical for plot and dialogue to be done by different people. So I have two questions: is that true, and if yes, is it often true even when there's only one credited writer?

It’s not common anymore, not in the actual split of one writer plotting and another doing the dialogue, but it still happens.

To do a comic ‘Marvel style’ is a different thing…the writer plots the book, the artist draws it, and the writer placed dialogue and captions over the art.

That’s still fairly common. Having two writers split the duties into plotting and dialogue is less common, usually happens to get caught up on the schedule a little bit.

I am not familiar with it happening with one credited writer, but I suppose it’s possible.