I don’t understand the ceiling outlets in the kitchen (and elsewhere, e.g. bathroom) at all. Some of them look like billiard balls scattered around the room. If you distribute more outlets, you either grid or halve, use diagonals, equal wall distances, central lines, third lines or whatever. But you can’t avoid having some logic if you don’t want it to look awkward. And yes, planning can become very exhausting.
Basically, you should already think in the kitchen about what you want to achieve with so many outlets. We don’t know if you really like spotlights or think there have to be floodlights everywhere now. You’re flexible with tracks. Do you know what you want above the stove? For example, the countertop lighting is integrated under or in wall cabinets. Those are then included in the kitchen order and each row only needs one socket because they are connected in series.
Open-plan area: I’ll just write what we have and how often or not we use it: 2 ceiling outlets in the kitchen over almost 5.5 meters length. Work area lighting under the wall cabinet, task light above the stove/island. Dimmed “table” lamp on a half-high cabinet. The work lighting is turned on very often, between 8 pm and 11 pm the dimmed light. Ceiling lighting very, very rarely. Dining area: one pendant light. Dimmed table lamp. The latter on from dusk until bedtime. Living area at one outlet three large pendant lamps hanging in the air centrally at height -> turned on 4 times a year. TV-side dimmed light -> on daily from dusk, sofa often floor lamp as task light (sewing, knitting, reading, playing etc). In the living and dining area, I would definitely make the main ceiling outlets dimmable.
In bedrooms I would plan one ceiling outlet, centrally positioned, and 2 sockets for bedside and floor lamps.
If the room is at least 16 sqm, I always plan 2 ceiling outlets. Do you think it is also necessary if the room is e.g. 16.5 sqm?
The bigger the room, the more you need. That’s why I don’t understand your question. Child 3 gets by with one ceiling outlet like Child 1. Bedroom too. But if you want the wardrobe illuminated, I would distribute four spots at window height parallel to the wardrobe, the fourth centrally in front of the door, positioning the others accordingly. A dresser manages well with a table lamp.
Should I have a cable installed for illuminated washbasins?
Definitely. That light is more important than harsh ceiling light.
Bedroom:
We currently have a 1.6m bed.
It’s similar with us, but we still have the 160 cm bed. Similar because a dresser is planned on the right side as with us. Measure the dresser from the wall side and then place the bed centrally from that. Switch also centrally from the bed. And if all that changes someday and the dresser goes away and the bed moves because it looks better that way, then that’s fine and not a problem.