You cannot say it at all. Of course, there is time needed to understand the concepts, but you cannot “master” the language, you can be very good at that. There will always be something that you did not know about, you always need to expand your knowledge. Even how long it takes for someone to write code quickly and well, is not set in stone, because everyone learns differently, and some people do not have the ability to understand the code or think in the way that it offers them to write good code quickly.
In general, the programmer himself must know his weaknesses and improve them. Only you can know where you are good and where you are bad, outside of oppinion can help, but there is no definite list of projects that you have to do to be considered “good”.
Femaref
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