Good observation. I've experienced the consequences of turnover on my current team. The product was mostly built 5 years ago, but no one on my team has been here more than 1.5 years. Getting even basic things done requires extensive codebase archaeology. It sucks.
I don't necessarily think you need the people who wrote the code originally though. As long as there's enough overlap between generations, and deliberate effort to train people on different parts of the system, knowledge can be preserved. That's probably not possible if everyone changes teams after 2 years though, except for relatively simple or highly standardized codebases.
I don't necessarily think you need the people who wrote the code originally though. As long as there's enough overlap between generations, and deliberate effort to train people on different parts of the system, knowledge can be preserved. That's probably not possible if everyone changes teams after 2 years though, except for relatively simple or highly standardized codebases.