SAKURA in KYOTO 2018 Back to Kansai
We've simply assumed that _positive_ effects are optional; _negative_ effects (adding construction time being the only example) are mandatory.
Well theoretically, that means walking through a room might mean adding build time but not taking the 2 VPs.
The build time seemed to be the only obvious negative effect. We couldn't see any harm in the other effects. So we assumed that tied the two effects together. And so any two effects are tied. Meaning a second effect is mandatory, not optional.