"And yes, I still think other factors should um.. "factor in" on the frequency of Great Citizen".
There already is a mechanic for building citizens if you want them more frequently. The higher your production the faster they can be built.
And since production is based on all the other "factors", they don't really need to be factored again IMO.
The question of whether they are too hard to build is another question all to together. You can probably mod the cost if you want more faster.
To your highlighted statement above.: Nobody said this in all of the threads I read on this topic. I've been lead to believe that the frequency was fixed at 1 citizen per 10 weeks and my gameplay reflects that. I have not observed what you say above. I only have a problem with the 1:10 ratio because it does not fit at all with how real people in their real communities work.
And yes to your observation about "being factored in again". You see, when real communities produce the best of the best and they do it over the course of multiple generations, this too has a compounding factor.
Better, stronger communities with strong education systems and moral codes tend to produce a greater number of outstanding citizens, who then build better, stronger communities with strong education systems and moral codes. Wash, rinse, repeat. Excellence would rise until great people begin to die off faster than they are created. Such a decline could happen for any number of reasons, such as War, disease, a broken education system, a broken code of laws, corruption in government or law enforcement, or any factor that might put downward pressure on excellence or cause a rapid depopulation event.
Interrupt any positive cycle, and the decline can happen just as quickly as the rise; sometimes in as short of a time as a single generation. I can't say if the Iridia, Yor, or Altarian cultures would experience this in their societies, but if you look at the great rise and fall cycles of human civilization over history and you'll see that I'm right. For humans, at least.
I guess since Crusades doesn't kill off its elderly "Great Citizens" (assuming I don't work 'em to death), then I guess it's balanced out. Sort of. Even so, I still have a problem with 1 every 10 turns being fixed with no other inputs deciding this.