One of the big assumptions I had a problem with: we would build monuments. I build zero more often than not, I'll just have subtly different city placement depending on whether I get free culture. With the Sacrificial Altar, I know in advance that a city won't need hammer tiles to pull its weight... so playing Aztecs affects my priorities long before I research CoL. This will result in different city placement, especially distribution of flood plains or food resource clumps, and may make me prioritise coastal/island spots that I'd otherwise neglect because of sub-par midgame potential. If having the Sacrificial Altar down the line makes me go for a Great Lighthouse economy from the start, that changes the entire game. Both Terrace and SA alter optimal early decisions to a significant extent rather than being "a little extra x thrown in". Rigorous analysis works if we can keep almost everything constant, or if things we change are easy to quantify. I've done my share of gratuitous maths (FIN vs. ORG, tile improvements and extreme lategame economies, cost-effectiveness of units, value of different unit promotions, GPP scaling, whipping efficiency...) but I don't think it's appropriate here.