They don't know birthdays, so when you use birthdays to solve their doubts, they may not accept your answers or refer to them. But there is no question of applicability.
When things happen, all solutions are applicable, just depending on whether you accept them or not.
There's a saying in China's fortune-telling world, if you believe it, you don't believe it. In fact, this statement is nonsense and is used by scammers to prevaricate. Real forecasters can only distinguish right from wrong, not believe it or not.
Therefore, the zodiac is also suitable for all the people tested.