Ceiling spot as lighting in the ceiling

I was told that if I order the drillings for spotlights starting from the [Deckenwerk], it could very well go wrong. My builder strongly advised against it because apparently in the past there have been incorrect/asymmetrical cutouts. However, I have ordered and received the 13cm drillings per room for the ventilation. I haven’t measured them myself. But they look fitting. However, a 13cm hole in each room corner is something different than 10 symmetrical spotlight holes.

P.S. I have received [Filigrandecken], which are 5cm thick; supposedly you can drill well there. The electrical wiring will be completely installed on the ceiling anyway. The ventilation too. Afterwards, everything will be cast with concrete.

I will take photos later.

We have also reduced the spots/ceiling housings to the kitchen and shower.

However, we also ordered the housings before pouring the ceiling.

For the remaining rooms, there are normal connections in the center of the room. We will purchase most of the lights only when the rooms are somewhat furnished and it becomes clear where light is needed.

With us, the housings fit perfectly. That is state of the art.

What is your general experience with GU10 LED spotlights? I have two ceiling lamps in my apartment, each with 3x GU10. I feel like they get too hot and break too quickly. The eBay ones are okay, but even the Osram 5.3W ones bought afterwards only last < 2 years. I am considering whether it might be smarter to switch to MR16, both in the hallway and later outside under the eaves. If the transformer is not inside the lamp, the heat generation (= lifespan) should be better, and there would be one large transformer instead of 5 (or more) individual transformers (each with loss). What do you think about that?? A few years ago, I installed MR16 spotlights from Aldi at our house entrance (previously halogen); they create such amazing light, both in color and brightness.

Today at Aldi there are 6W GU10 for €2.50 with Ra>97; 3000K; 345lm; 60°.

I bought 3 pieces and find them significantly better than the 5,xW from Philips.
I haven't tried Ledon yet. They are not as bright as the 7/8W Ebay(Lichtrevolution) ones, but those don't last long either.

What are your experiences with Aldi LED bulbs?

Error: 40°

The higher the Ra value, the worse the efficiency I have read.
That means 6W Ra 97 is about as bright as 4.3W Ra80 or similar.