It was a new house. The 18 AP locations serve a couple of different long run purposes and reasons:
The first is to have direct nearly-line of sight locations for the majority of the house which is primarily to support higher frequency(60GHz) and beyond which have poor wall penetration.
The second is to provide good wifi coverage due to signal attenuation from the construction techniques. I did many of the walls in double 5/8s drywall, some in green wall, all insulated, and all solid hard doors. Steel cross structures as well. As a result wifi propagation is surprisingly bad across rooms.
The third is to provide lots of locations to aid in flexibility of having the best locations. I do not use all 18 locations right now, but I may use more in the future.
It is also a somewhat large (>10,000 sq ft, ~ 1000 sq meters) house, so that facilitates a need for a bit more coverage.
I'm using Ubiquity Unifi 6 Pros right now, but am going to switch to the Enterprise ones (with 6Ghz) at some point soon. They are all integrated to the same controller (a UDM Pro), so all SSIDs I use are available everywhere. I even have a couple of them down the driveway all the way to the gate so I have wifi coverage all the way out.
> I did many of the walls in double 5/8s drywall, some in green wall, all insulated, and all solid hard doors
I gather you did this for noise isolation? And by green wall do you mean green glue between the drywall layers? I'm only familiar with this for home theater construction, not an entire home.
