Repetition reminds people of the brand. Let me ask you a question. If you get a small cut or abrasion on your finger or arm what do you put on it? Most will instantly say a "band-aid", but band-aid is a brand when the actual product is an adhesive bandage. People who are over 30 years old probably remember the old jingle "I am stuck on band-aid because band-aid stuck on me".
Joseph Goebbels, the propaganda minister for Hitler stated the following: “If you tell a lie big enough and keep repeating it, people will eventually come to believe it. The lie can be maintained only for such time as the State can shield the people from the political, economic and/or military consequences of the lie. It thus becomes vitally important for the State to use all of its powers to repress dissent, for the truth is the mortal enemy of the lie, and thus by extension, the truth is the greatest enemy of the State.”
If someone is exposed to the same thing over and over it becomes their reality and this is the reason they play the same commercials over and over. So yes, there is a reason for it. You will also notice they use the same people for the commercials because it builds trust and you feel like you know them, and that brings trust, where you like it, believe it or not. The reason they do it is because it works.