Seperate scales on each page

Can it be true that this is not possible (or is it just me that can't figure out the right way?)?:

Page 1: Drawing a scale 1:100 of the building

Page 2: Drawing a detailed plan of one room in scale 1:20 without changing the scale of page 1

I know this can be accomplished if I turn of dynamic dimensions, but this is only convenient if I page 1 is entirely correct before I start page 2. Often you are working on a whole project switching between the pages and then you have to change scale settings every time...

What I am hoping to be possible to do, is to set different scales for each page without affecting the scale settings of other pages, just as it is possible to set different page sizes like this