Do you mean for each default civic or all default civics?
[D * [ O * ( [ P * (N-10) ] + [ C * (M +1) ] ) ] ]
-10 and +1 are the median
Slavery, rest, low is
Each low civic is about
.08 * (n-10) + .4 * (m+1)=
.08 * n + .4 * m -.4
Organized saves .04 n + .2 m - .2
slavery is
.12 * (n-10) + .5 * (m+1) =
.12 *n + .5 *m -.7
Organized saves .06 n + .25 m - .35
Total cost
.44 n + 2.1* m -2.3
So you mean for all civics. If 40% of your population are working 2 commerce tiles, you gain
0.4 n = .22 n + 1.05 m -1.15
.18 n = 1.05 m - 1.15
With 6 cities, then 5.15 = .18 n, n = 29, or an average of 5 population each city.
I think 1/3's a bit more honest mid game (hr no bureaucracy) 6 cities total population of 45, average of about 7.5.
Might as well list them all
If most of your cottages are in your library/academy capital, it should be better for financial.
There's other factors, like financial makes non-riverside cottages return their value in 15 turns as opposed to 30, if you assume 1gpt per pop from some arbitrary hereditary rule deity calculation.
Financial you can switch mines to riverside cottages at 3 to 2 instead of 1 to 1 to make up for faster expansion vs no economic traits, although I guess organized does this too, and perhaps better since it scales better with #cities and lower average population. The biggest difference I notice is that courthouses can be worthwhile investments for organized leaders midgame, whereas non-organized you're usually better off building wealth and running specialists instead of whipping.