It depends on what and how much one is learning from it. I once interviewed a guy for an ETL developer role. He was supporting an ETL application. In four years

It depends on what and how much one is learning from it. I once interviewed a guy for an ETL developer role. He was supporting an ETL application. In four years, all he had done was restart the application in case of any issues and it somehow worked for him. I've seen my fair share of such cases.