It's purely based on a game where your neighbours are active enough to polish them all. It wouldn't hurt to add some culture buildings that use up less space but give more culture so at least people can maintain 140% or even 170% easier without having to use half of the space they have.
Its NOT based on your neighbourhood. As i mentioned in another thread even the 8 hour polishing time is much too short to be effective.
Mostly you get nothing from polishing in my and many other cases because the whole polishing time is wasted while you are at work or something. First and foremost we Need the 12 hours polishing like FoE has.
Take as example that you have 50 active neighbours who has discovered you. The first 5 polishing all your buildings (only fictive number) and the remaining 45 visiting you while the polish is active and then don't have time to visit you again this day. So you get in worst case 8 hours polishing shortly after going to work and you have nothing left of this when you come back.
As an example from FoE. I have an really active guild and neighbourhood there. I usually get 100+ polishes and motivations per day. And at least 3 days a week its NOT enough to cover my "cultural" Needs.
Upgrading cultural buildings would be a huge contra for Inno Money wise - especially when you could upgrade Diamond culture for ressources. Thats a massive loss for them because you will skip 2-3 tiers of Diamond culture before buying new ones.
The cultural Need are definately much too high atm. And thats even in my Progress Level. I mostly Need one new holy Codex for one Major building upgrade (Main Hall / Barracks etc.).