No. Sub-pages would be a way of easily creating 'categories'. With the data i'm dealing with, really the only difference between a page and category is how it's displayed. The sections would be the content displayed within the page.
Say I had apage on architecture. This page on architecture would have lots of content broken up into sections. There would be an introduction section, a styles section, a materials section etc. Each section would consist mainly of a title, a body of text and maybe a few images.
Each section may have sub-sections. For example the styles section may have subsections georgian, roman or egyptian architecture.
Then say I come along and expand the georgian architecture section. It becomes really big, in fact so big that it should be its own page. So I separate it into it's own page but it is still really a part of the architecture page, it should be under an architecture category. Making it a sub-page is a way of creating that category without knowledge it was needed before hand.
Data used in both a category and page are the same, just displayed differently depending on whether they have children. This is also convenient as the situation arises where it is better to display a page with children as a page and not a category. It's a bit hard to explain, but it's the best way to display my content and have that flexibility. I think.
Does that make sense?