In old versions of KDE (was it 4.x?), it was easy to select, for instance, printing several pages per sheet directly from the main window of the printing assistant. 

Now you need to open the printer properties first, then "Page" tab.

In my opinion, the whole "Page" tab has little to do with printer properties (except for margins, you may want to set these options independently from the actual printer you will use) and a lot to do with what you actually want to print. Hence, it should be moved to the main dialogue. It could be just another tab next to "Copies", "Options", and "PDF options".

Probably, it should actually be merged with "Options", as double-sided printing options are the same kind of settings (i.e.: this is all about how pages are being laid out on sheets in order to produce the printable document). Then the tab could be renamed "Page options".