the issue claims that leaders in any profession should step down after 5 years, which is the surest path for an enterprise to revitalize. I admit that new leadership is a way of renovation and bring new blood to the enterprise. However, this should not be a universal approach for any institutions, departments to apply.
at first, i have to admit that by changing the leadership, is a way of bring fresh blood to an enterprise. there are many cases where we make an institution active by bringing a new leader. For example, back in 1993, when IBM was suffering great loss, Louis was appointed as the new CEO, aiming at change the bad situation. After Louis came, he made a huge change to this company, brought his new ideas, changed the way they do business, finally, in 1994, IBM was dragged out of the mess. From this case, it is not hard to see how could a new leadership benefit the company when necessary.

However, this approach cannot be applied everywhere. Here we want to revitalize there is no point to change the leadership if the leader himself or herself is innovative enough or her or himself can find a way of revitalize without being replaced by others. For example, my friend father, was appointed by a State-run chinese company as the manager, and he had doing this job for 20 years. Similarly with Louis, he was appointed to save the company. However, because of his strong leadership, he united the company where employees used to have no loyalty and no innovation. by employing new technology and building employees loyalty, the company has been the leader of that industry since the inauguration of my friend's father. in this case, it is not hard to see that a good manager who keeps revitalizing himself may not need to step down every 5 years. 
besides, there are defects comes with this frequent change of leadership. one of them would be the inconsistency between two leaderships. In political area, this could result in bad results. Personally, i have an experience like this. in the city where i live, the change of city major brought really bad effects to 10,000 residents. The previous city mayor had different developing ideas with the current one. thus, according to the plan of the previous major, the place where i lived should be residence area, so developers build some nice apartments there. however, last summer, when i was in China, i heard a terrible news, that the new city major would want that area to be part of a river by bring water from the nearby river.  thus, our apartments, which was just finished constructing in 2002, was announced to be torn down in 2009, due to the inconsistency of leader plans.