Without accepting guru, the name one chants is not transcendental. That name will fulfill your worldly desires, even up to mukti (liberation), but not more than this. In the case of Ajamila, at first he had no guru. He named his son Narayana at the nama-samskara, the ritualistic ceremony in which babies are given their name. By chance...

This is our object as well, but as far as we are concerned, we waste so much of our time and energy in maintenance. Though we are devotees, our whole time is entangled and we have no time for remembering and chanting. We think, "If we give our whole time to devotional activities, our business will fail. How, then, will we be able to maintain ourselves?" We have no belief in Krsna, and we have no belief that He will continue our maintenance. He is the main root of our maintenance...

by Śrī Śrīmad Bhaktivedānta Narāyaṇa Gosvāmī Mahārāja

Those who remain under the shelter of śrī guru will experience intense waves of separation from him when he is no longer manifest, and those waves will surely increase to their utmost magnitude.

There are many gradations of bhakti and bhaktas, as explained by Srila Sanatana Gosvami in his Brhat Bhagavatamrta. The first category is the sakama-bhakta, then the jnani-bhakta, then the suddha (pure) bhakta, the premi-bhakta, the premapara-bhakta, and finally the prematura-bhakta...