Thanks for the suggestions. Time management is indeed not thoroughly consistent. I just wanted 18:00 as cutoff date for exploration so I have some mandatory time left for evening events.
That probably needs some polish (there is no engine restrictions, time passing is just a simple variable progression)
The anomaly 20:00 rationale is that you need some time to bring V onboard and it takes all day until 20:00. But its only a solo event.