I am asking this question because I have rarely seen this striking phenomenon addressed in other questions.
By "interaction "effects, I'm referring to the fact that if you buy a production building such as a small sugar mill, you get one victory point (VP) and if you buy the guild hall, you get 4 VPs, and 1+4=5 VP. But if you buy them both in tandem, you get the aforementioned 5 VPs, plus a bonus VP (the interaction effect), for a total of 6 VP. Likewise, if you buy a "violet" (non-production) building plus the city hall, you get (1-4) VPs "standalone" for each violet building, four for city hall, and one bonus VP for each violet building (the interaction term).
Do such synergies cause people to think, "I'm going to "max out" on production or violet buildings and buy the guild hall or city hall, respectively?" Or the reverse, I'm going to buy the guild hall/city hall ASAP and "max out on production/violet buildings afterwards? And would a production-oriented person who has bought a guild hall think, "My main opponent has a lot of violet VPs, so I'd better buy city hall before he does to deprive him/her of those "interaction" VP's even though city hall is worth only 4 VPs to me?"
Or are there better uses for your resources than the ones I've described above?