The reason why it's only 4+8 hours is to give factions not enough time to plan everything with all other factions properly. Way more chaotic this way.
Chaotic means more scrambled.
More scrambled means more action.
We're thinking about moving it to 16:00 CET though.
Also, the first 4 hours are just setup time - which means it doesn't matter if you join at the beginning or the end of the 4 hours.