Blessings! I have a question about Japa practice. Is it best to chant the same mantra all the time. To find one that resonates within and chant only that. I find that I tend to want to chant certain mantras at certain times.
The terms japa, chanting, and mantra have different meanings. I thought to explain these differences before answering your question more specifically.
Japa means a continuous saying (out loud or mentally) of one of the names of God or Guru. Usually it is very short such as "Hare Krishna" or "Sri Ram, Jai Ram" — something like that.
For people on our path, Swami Kriyananda has recommended a very simple but powerful one for us to use: "Om Guru!"
A chant is a prayer or an affirmation set to music, such as "Door of my heart, open wide I keep for Thee..." or "Lord, I am Thine, be Thou mine!"
A mantra is a set of words (sounds), generally in Sanskrit, which contains specific powers or very high sound vibrations. An example would be "Hong-Sau" which is used in connection with observing the breath, in Yogananda’s path of Kriya Yoga.
Now to specifically answer your question: It is probably best for you to do that which seems to be helping you most at any particular time. However, switching around a lot might have the "down-side" of not letting you go really deep into any one japa phrase.
Certainly with chanting it’s fine to sing a chant which resonates with how you are feeling or what you are needing in your life at that time.