Vaishnava Samhita: Prakashananda Charitam. Vol II Book 4 Chp 16 Shloka 31
न जानामि फलं तस्य न जानामि च वैभवम् |
कृष्णस्य मधुरं नाम जिह्वायां नृत्यति स्वयम् ||
Na Jaanaami Phalam Tasya Na Jaanaami Cha Vaibhavam
Krishnasya Madhuram Naama Jihvaayaam Nrutyati Svayam
Shri Chaitanya Mahaprabhu replied
I do not know the full potency or the fruitful benefit of chanting the Divine Names. The sweet Name of Shri Krishna dances on my tongue of its own accord.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji
The more you chant a Mantra, the quicker you realize its potency. From that perspective, one gets the unlimited privilege of chanting the Maha Mantra any where and anytime. So this Mantra is alone enough.