Is full-surface putty work absolutely necessary?

Hello, We are currently building and my question is: do the walls need to be completely filled with putty for wallpapering and painting? We wanted to limit ourselves to the edges and joints since the walls are otherwise very, very smooth. Is that sufficient?

what do you want to put on it? Textured wallpaper or paint directly?

If you want it smooth then leave it

Raufaser on the top and bottom will probably be fleece or a nice Raufaser

With painting fleece, you will probably have to do some filling in Q3, unless you have no problem with the joints being visible in raking light.