I... uh, wouldn't consider a text dump of a full novel getting completely typeset as a good example to consider when talking about sites?
Are there ereaders that have to typeset the entire text of what you are reading? What is the advantage of making the task harder?
Still, I should acknowledge you provided an example. It surprises me.
As often as the font size changes.
Even the few times I do change text size on my e-readers are largely mistakes. Having gestures to resize is frustrating, in the extreme.
When I'm home, I read books.