I see this statement over and over again in eastern religious literature.
So I would say that it is important to understand why one should chant and understand what the syllables mean as well.
Then again there are many different understandings for why one should chant.
1. In TM one says the same word over and over in order to turn off the vocal part of the mind, like the left side, and allow the emotional or spiritual side to come through.
2. In Hinduism you chant the names of god in order to be saved at the end of your life. It is considered most beneficial to do so right at the end
3. In Buddhism, according to the Tibetian Book of the Dead, you call out to the Lord of Great Compassion after you die as well as before.
4. In Born Again Christianity you just recite a certain phrase and you are born again. I do not know if it is necessary to recite it over and over again. Probably not, as Jesus told us not to say the same things over and over. So Jesus was against chanting. Did you know that?
5. I chant to heal various aspects of my body and soul. So my chanting is purely selfish.
6. BTW- Mother Mary at Fatima told us that if enough of us say the Rosary often enough every day, she will be able to convert Russia. One may glean much understanding from that statement.
6a. First of all Mother Mary was endorsing chanting in opposition to her son.
6b. Just as important, she needed the energy of humans chanting to accomplish the conversion.
The Russians have a theory that explains this. See my article on the-atlantic-paranormal-society.com site. It provides a link to a more thorough review of the Russian work. I have not found a direct source of the Russian work yet.
Anyway, my impression is that all these understandings are correct. Chanting has many effects, and they are not all necessarily good- you can chant up evil spirits as well, without intending to do so.
7. In the Russian theory, actions have the same effect as chanting, for good and for bad.
I am sure there are other understandings that I do not know about.