Call me naive, but I would presume that even a junior, once they start working at a company, should be familiar enough with a language that they know all the basic syntax, idioms etc. Still, even if they are, over-using some language features will make your code less readable (to anyone). E.g. some will prefer good ol' if/else to the notorious ternary operator and its many descendants. But that brings us back to your own personal taste...