In my experience (math, small european university), this is the romantic idea of a Ph.D. more than how it ends up being in practice.
In my case (and quite a few others around me), a Ph.D. is some research of varying novelty and complexity, far from making you an expert in the subject(s) at hand, but hopefully enough for your committee to think you deserve the title. In the cases I'm talking about, you're far from becoming this idealized "expert in your specific subfield" with new insights and that further researchers will base their work on; it's mostly grabbing whatever small questions you can try to explore and if possible answering them.
Still, I think the idealized version does hold for quite a few people, if not all of us.
I think it depends on the field, and on factors like quality of advisor, quality of peers, how much teaching you have to do, etc.
In CS, for example, people definitely come out as experts in some niche of their research. Of course, there's a difference between their expertise and that of an experienced professor, but both are quite far from a normal person's knowledge of the field.
rosetremiere|4 years ago
Ar-Curunir|4 years ago
In CS, for example, people definitely come out as experts in some niche of their research. Of course, there's a difference between their expertise and that of an experienced professor, but both are quite far from a normal person's knowledge of the field.
morelandjs|4 years ago