Working with a big legacy code base is an infinite source of teaching and knowledge, especially around system architecture; what works, what doesn't work, how t

Working with a big legacy code base is an infinite source of teaching and knowledge, especially around system architecture; what works, what doesn't work, how the craziest workarounds can make something impossible possible, how APIs with the best intention got abused over time, value of tests and where to test, how to read code rather than just write code, and so on. Simply it gives you wisdom, rather than you reinventing the wheel to find things out along the way. I wouldn't want to do it forever but for a junior to try it out at least once is an important life lesson.