The only exception to this rule were Cultivators like William, who did as they pleased. If he wanted to take a Tribulation in the middle of Blue Moon City, who could stop him? In fact, he was still being punished by the Eternal Tribulation, he didn't have a choice!
William wouldn't do that, though, unless he hated the city.
Because of the Eternal Tribulation, William often found himself intentionally avoiding populated areas in case he causes an accident. Only when he needed to buy some things from within did he use the Illusion Territory or Stealth Talent to hide from the Tribulation.
Seeing all the other Cultivators attempt Ascension one at a time, William felt pressed to speed up his own activities. With the mapping complete and thousands of Companion Beasts at or near the peak of the World, William could finally begin his System Quests.