Have you ever heard Phase One explain their process for profiling a camera? I have from several Phase One employees independently and the amount of work that they put into every camera's profiles is extraordinary and far exceeds what Adobe does.It's one of the reasons why they often don't have C1 ready for new cameras the day they start shipping as they procure actual production cameras and then profile them using a test suite that includes about 700 actual photos to zero in on their profiles.
This sounds a bit strange, you can't just have 700 photos laying around and profile any camera against that, you need to
shoot those 700 scenes with the new camera then. Or you measure the camera's SSFs and you have 700 photos captured with a full spectrum camera and render virtual raws from that which is theoretically possible (that feature exists in DCamProf by the way) but I doubt they do that. Or maybe they just shoot
prints of 700 photos in a viewing booth, I guess that would sort of work but it's not true to the spectrum so it seems to me to be a poorer method than simply shooting a smaller number of real scenes plus some fixed reference test target scenes.
It's also the case that a camera profile is global and static, you will need to make tradeoffs. You can't make a profile that's best for all types of subjects, so to make it better for skin you may need to make it worse for landscape. So testing it on 700 photos doesn't mean that you can make it perform at the same excellent level on all those 700 (unless it's 700 photos of the same subject), but you need to pick and choose what you think is more important and what is less.
I also assume that they put a lot more manual tuning effort into say a IQ3 100MP profile than say a Canon 1DX profile.
Finally it's a lot of subjectivity involved in these profiles, and if your personal taste happen to
not match the profile designer's it doesn't matter how much time that has been spent with the profile. I find this true with Phase One's look, sure the profiles are extremely well-made and robust, but I just don't like the yellow cast (which is there by design as Phase One likes that look) so to me a custom profile made using simpler methods than they use suits me better. Many like Phase One's look though obviously, but my point is that camera color is not a linear scale from bad to great, there's a lot of subjectivity and tradeoffs involved which means that the complexity of the design method does not really say that much of how well the profile will work out for a particular user.