Even after making it all the way to the airlines there is still studying to be done. You would think you go to school, get your education and ratings and then that’s it right? I do not remember anyone telling me about recurrent training and additional learning courses during the year. This equates to a tremendous amount of homework and preperation. Most airlines require that you do some sort of recurrent training one to two times per year. If you decide to switch aircraft you will be looking at an initial training course between two and three months per aircraft. If you are not in the airlines but fly something that requires a type rating, its very simliar. Generally the type rating course is about a month long (or longer) and you will have to do a recurrent once a year.
General aviation has their version as well in the form of a biennial flight review. Not so much homework, but its still good to brush up.