(1) is fast and may be approved in some countries. The patent right can be licensed, transferred and used for other purposes.
(2) Reasons that can be used to fully convince examiners in other countries to make authorization decisions after obtaining patents in some countries, such as German patents and European patents.
(3) If you only intend to apply for a patent in one or two countries, the cost of this method is relatively low, and because of the independence of the patent system, applying for a patent in multiple countries may be approved in some countries, at least in some countries that implement the registration system.
Disadvantages: 1) The longest time to apply for going abroad is 12 months, and all foreign documents must be translated and submitted within 12 months, which is rather hasty; 2) Various forms and languages are required for submission.