I don't believe US banknotes change design that frequently. In europe bank notes change design every 5-10 years and quickly stop being legal tender a 3-5 years afterwards...
We had a major redesign in about... 2001ish. You still see the old notes circling around sometimes and they are still legal tender. The $100 bill was redesigned about two years ago. We have new paper notes coming out soon... https://modernmoney.treasury.gov.