Interesting.
Are you planning some work in this area?
Personally, I find myself very often chosing the Family focus, even though imo it is pretty bland in regards to content, but I am such a naive and idealistic guy that I always try to make my spouses like each other ^^
Then I also often switch to Combat focus before a planned war, to get some more troops.
Frankly, I haven't used the other foci frequently lately, but then I haven't really played (only tested) in a while. I still feel they all fill a nice niche, even though content differs vastly in quality. For example:
Family focus feels like it is always only about opinion, which is very boring albeit useful.
I really used to hate the buisness focus, or whatever it was that let me build up fountain and a hedge maze, and get it as a stupid character modifier. But that was before Paradox revised their policy of making literally everything into a character modifier...
Combat Focus, for comparison, feels a bit more thought out overall, and I couldn't say what would need changing there from the top of my head. Well, apart from Duel Engine, but that isn't the focus itself.
Well, I will be curious what the survey will tell...