When you carry a half empty vessel, it makes more noise as compared to filled one. In the same way, a person who knows less, pretends to know more and tries to act smart. On the other hand, a knowledgeable person is like a filled vessel who makes no noise or tries to pretend to be smart. His/her knowledge speaks on behalf of that person.
This means that until something is completed 100%, do not consider it complete. At a lot of times, we think it is over, because it is almost over, but there are always unforeseen factors at play in life, which lead to taking much longer to finish the last bits of something.