The question is ill-defined, it's like asking in how many hours can you learn to program in, say, R. The answers can plausibly range from "a few hours" to "a lifetime".

Besides, in this case some skills will be general (e.g. risk management), equivalent to the ability to code, and some will be very very specific (e.g. knowledge of the regulatory regime in a particular narrow field), equivalent to understanding some library very well.