Or attended a conference and struggled to remember the following year whether you attended it or not – much less whether you actually learned anything?
Or led your organization through significant market research and strategizing only to find a year later that things remain pretty much the same?
Common sense and lot of research back up the idea that we don’t retain very well what we don’t use. The simple (which is not to say easy) solution, of course, is to apply new knowledge or skills soon and frequently after they are acquired. This goes both for individuals and organizations.