Best unified affinity gain is from harmonized settlement (might be inner imperial city now). Targeted affinity gain is from the wilderness where you have the wander setting enabled.
Viewing post in Cycle of the First Dawn comments
Honestly I never checked the wildnerness after realizing that harmonized provides a unified bonus. I'll just test the wilderness wandering and see if affinity increases.
Mono Outer: Doesn't not do it, or its very slow. Didn't see any gain in 500 years
Mono Inner: Wandering does not increase affinity. same as above
Dual Outer: Wandering does increase it but at horrible rates, harmonized settlement is superior.
Dual Inner : Marginally better than Outer
Mono Deep: Same Pace as Inner/Outer.
I agree with your wilderness findings, they are most definitely broken because I remember getting far better returns from wilderness for affinity gains. I also am not sure if this is because I'm band 17