In genealogy and family history work, conclusions about relationships can change whenever better evidence is discovered. Similarly, current understandings are subject to change as more data becomes available and the understanding of this data improves. This is also the case with generation length; so don’t feel that you must follow the latest convention, using a length that you feel comfortable with is fine. The length of a generation and using them as a tool to researching your family history is a great way of checking your findings as well as making an unexpected discovery; you never know what you might stumble into.