Not all, but all connected (also connections in the background).

Yes you are right a lot of pages for a small adjustment. But x5 can not always determent if it has connections, so if you update a page, all pages that are on any way connected are also updated. that is just to make sure your website keeps working correct.

The other way around might give in some cases trouble and then your website is incomplete.

So in short x5 wants to be save instead of sorry.