Although one is chanting ceaselessly, one will still be reborn in Samsara if sentimentality is within one’s mind ; But if we have utmost sincerity and let go of all mundane concerns, then that very state of mind will bring us right up to the Pure land of Amitabha Buddha. 
On the other hand, if one is attached to the various relationships and mundane concerns; unable to let go and renounce; then even practicing for10,000 years will not free one from Samsara.
 It is all about our mind
The ultimate goal in Buddhism is to achieve enlightenment so that we do not need to take another tour of Samsara. This is because Samsara has many faults and is full of opportunities for sufferings. BTW, Samsara includes the various heavens.
To reach enlightenment, our mind must be free from Samsara.
Sentimentality in our mind refers to that sentimental attachment we have about our life. Our childhood memories, our happy and even biter moments, our relationships and etc. Even situations that we were opposed to or annoyed with can become sentimental. You know, like how older people like to reminisce? That binds us to Samsara. It is our discursive mind living in the past. It is almost like we are “living” in a different world or different time when we reminisce.
Similarly, fantasizing about a future also creates sentimentality. It also creates “worlds of fantasies” in our mind.
Since we have millions of such thoughts, we created millions of such worlds in our mind. Samsaric worlds.
Although chanting may appear different from meditation outwardly, the goal in mind training is the same. We cannot mistaken chanting to have different goals. We still need to practice for a non-discursive mind.
When we are focused and concentrated. Jhana / Samadhi appears in our mind.
 Relying on faith and sincerity
For some people, it is easier to rely on faith and sincerity. These are very powerful mental faculties that past masters had relied on. Instead of reading through volumes of sutras and books, they prefer to pray and rely on their faith in a Buddha or Sutra.
For example, in the story of Acharn Mun; a group of remote villagers who had never seen a monk and mistaken Him to be a Tiger Spirit (They only knew shamanism). Acharn Mun “tricked” them into chanting the word “Buddho” by telling them it is a magic incantation. (without denying that He is a tiger spirit) Consequently, their “simply” practice helped them achieve purity of mind. (Jhana) Then Acharn Mun helped some of them attain enlightenment.
If we have faith in a particular Buddha or sutra, then we can simply rely on that mental strength to achieve our “one pointed concentration” in our practice. (Aka. Jhana / Samadhi) [Refer to Kevatta Sutta posts for more background information about Buddha’s instruction on practices)
 Importance of letting go
Since the objective of enlightenment is to be freed from Samsara, it is important for us to let it go.
In Buddhism, there is no higher gods/goddesses lording over us or enslaving us to Samsara. We can all become enlightened and be freed.
For most of us, thoughts of our love ones, environments, life, works, hobbies and etc; creates that attachment that binds us to Samsara. In another word, we become attached and refuse to leave a dire situations
 It is the quality that counts
Finally, it is important to do it right, Although practice makes perfect, we shouldn’t mistaken that practice as our final goal.
The number of times we chant a mantra or Buddha’s name doesn’t matter if we chant without achieving Jhana/Samadhi. Although some sutras mention a quantity to be achieved, we mustn’t fool ourselves into thinking that mere chanting without the required mental states suffice.
To illustrate this simply, chanting a mantra while murdering people or slaughtering animals surely doesn’t make one a Buddha. (make sense?)
Buddhism is all about mind training and some schools of Buddhism had utilized skillful methods to “train” people of ancient times who adhere to non-Buddhist spiritualism. Just like how Acharn Mun trained the remote villagers who were shamanistic.
Chanting mantra in Buddhism is not about “invoking” a Buddha or Bodhisattva. (that is not a Buddhist system)
May all be well and happy