Peace Corps is most effective when new volunteers replace old ones, building a legacy of interaction with the USA in a small community.
My input group had around 70 volunteers because Peace Corps was receiving excellent funding at the time of our recruitment. Our large group expanded the presence of Peace Corps in Rwanda. Most of our sites (the villages where we work), had never seen a volunteer before.
However, once I was installed at my site, I learned that the input groups of future years would be smaller, around 20-30 volunteers per year. Some of the sites which had never seen an American before might not see one again anytime soon, and their Peace Corps experience would be just another bizarre interruption from the western world. That is why, until today, volunteers have been waiting anxiously, hoping to hear that they will receive a replacement at their site.