Electrical planning / lighting planning / network for new construction - experiences?

Photovoltaic 50mm is enough - should be exclusive for that. I currently have only two strings, still considering adding a third. Having a reserve is good.

Kitchen: Definitely ceiling outlets above the countertops and any possible table. Endless sockets, also at possible seating positions, whether for toaster or phone charging.

In the living room, I installed everything I need for the TV at two possible positions - I have already used it. In the basement, I partly installed only one ceiling outlet per room, that was a bad idea, a massive hassle afterward to neatly (!) mount three lamps there.

In my music room, I laid dedicated, directly routed (thus half the cable length) cables with a larger cross-section from the distribution to the amplifiers. In the garage, a really thick cable for a possible electric car.

I also installed reserve lines under the roof for possible spotlights, in the basement simply in all waste pipe enclosures as well as in every toilet a cable for possible high-tech toilets. Wherever I might want to hang artwork, an outlet opposite on the wall.

In my house, I have a total of 16 satellite sockets, 25 speaker runs, and 120 network ports. That is certainly overkill, but I have already used surprisingly many of them and above all: You never know beforehand which ones you will never use after 40 years.

In the next house, I would separate lighting and sockets. Everything that illuminates escape routes, I would secure separately.