Thanks to all for comments. I like to use parts only from one or two sets. Whereas on one hand it is more easy because you have all parts available, on the other hand it is a good challenge and a good exercise to optimize the work. It is a challenge in the challenge to use the big number of bricks you can.
Here there are also the details of interiors, but they are not accurate like outside.
You can see other two alternative models in my MOCpages, like this castle-theme one from set 7091: