What does a "classic" electrical installation look like?

Electricity flows "analog," i.e., without protocol headers, and is therefore only selectively addressable behind switches. The trend towards centralizable controls will increase; therefore, I would nowadays also tend to wire energy distributions in a "star-shaped" manner in case of doubt.

Technically it works. At least partially. But that's not how you do it. You would forcibly have 2 circles in some kind of box. If they are still on different phases then it is almost a short circuit.

I don't quite understand that yet. Where is the problem? The only seemingly wrong thing is having to go down to 2.5mm with the construction. 5x1.5mm should normally be enough, especially at the lengths mentioned.

I don't quite understand that yet. Where is the problem? The only supposedly wrong thing is having to go to 2.5mm for the construction. 5x1.5mm should normally be sufficient, especially for the mentioned lengths.

As I said. Technically, it all works, but whether it complies with standards - I believe not. In new construction or renovation, where everything is open anyway, you definitely don't do it that way. If you do it, then a disconnection device must definitely be used, for example an RCD that then disconnects the circuit all-pole, but then you might as well put everything on one circuit and avoid this discussion altogether. Google "one cable two circuits." It's often a controversial topic.