The time in the Celestial Court and the Mortal World are different, what does this mean? Simply put, time passes faster in heaven, while it's slower on earth, which is referred to as a sense of delay.
However, the difference is not too brutal. The so-called "one day in the mountains equals a thousand years on earth" doesn't actually exist.
The ancestral master once said that the concept of 'time' is an imaginary product and does not exist. What truly exists, be it a person or event, is the only genuine existence, and this is the true meaning of existence being eternal.
The various divine courts are able to co-exist simultaneously because they really did exist at some point. Gods who have existed won't step down from their divine thrones. They've simply chosen to slumber, because what else is there to do when the divine court is just too boring?