With the fast growing and expansion of knowledge in every field and profession, your existing Stock of knowledge is becoming neglected at a faster rate than before. If possibly, let take a trip round the world in sailing yacht and be gone for years and over, when you're back from the journey, you would realize that about 40 - 50% of all the knowledge accumulated is what justify the person position and salary in your business was no longer in vogue or valid and talkless of it being in used anymore.
You might even been thinking of beginning over again and your industry or business entity might no longer be in existence. In some profession nowadays, the rate at which the knowledge is been neglected is faster than others. For example, considering the knowledge of being librarian or historian comparing this field the knowledge of stockbroker is quite different.
The time frame for historian or librarian might take with 10 - 15 year before the knowledge become obsolete. The knowledge of stockbroker about the price of share interested rate, economics condition of market, market dynamic may be neglected within few seconds and few other days. One essential economic or political event can also change or alter opinion poll to make the accumulated knowledge in respect to election be neglected over night and develop a new secnerio.