Sadhu-sanga is required and essential at all levels. Even if you are advanced and you are a pure devotee, even at that time you would never give up sadhu-sanga.
It is recommended that one decorate one’s neck with these four ornaments all the time: humility, tolerance, not hankering for self-honor and ready to offer all respect to others.
As you sing the songs of Narottama Dasa Thakura all the teachings of the Vedas are there. How much surrendered souls we are, how much purified souls we are- to that degree we understand that song of Narottama Dasa Thakura.
Even if unserious persons perform devotional service according to regulative principles during kartika within the jurisdiction of Mathura in India, they are very easily awarded Lord’s personal service.