There is no problem with the Master Style. The problem arises when using the Master Style AND a Custom Style for a subset of pages on the same website.
Let's say I have a site with 100 pages. On 80 of them I use the Master Style, no problem, but on 20 of the pages I want to use an alternative style. I then
1. make a new page, deselect "use master style", tweak the style settings, and save the custom style as "My Alternative Style".
2. I then create the other 19 pages and apply the custom style "My Alternative Style" to them (after unticking "use master style"). All is now great until:
3. Later on, if I want to make a change to "My Alternative Style" on all 20 pages, I have to go to one of those 20 pages, make the change, and chose "update custom style with current settings". THEN I have to go to the other 19 pages, one at a time, and select "My Alternative Style" for the pages to reflect the new changes.
Rapidweaver should, in my opinion, update the other 19 pages automatically - I can't see why it shouldn't! After all, this is how the Master Style works. And it really does not make sense that it is possible for "My Alternative Style" to be different on different pages (until you manually update it on every page using it).
NOTE: my post title "One custom style to rule them all" may be a bit confusing. I don't mean that a custom style should replace the Master Style or anything like that. Just that updates to a custom style should actually update that custom style on all pages using it.