People often assume a bhajan set is a list of songs played in order. It is closer to a single long arc with recognisable stages, and knowing the stages makes it much easier to host well, because you stop interrupting them.
it starts slower than you expect
Almost every set opens below the energy the room eventually reaches. This is deliberate and it is not the musicians warming up.
An opening bhajan is doing a specific job: establishing the key, letting people find the melody, and giving anyone still settling a chance to settle without missing anything. Sing-along participation is a confidence problem more than a knowledge problem. People join once they are sure of the tune, and the opening exists to make them sure.
If a set opened at full intensity, most of the room would never catch up.
call and response is the engine
Nearly all congregational devotional music works on call and response. A line is sung, the room repeats it. That structure is doing several things at once.
It teaches the melody in real time, so nobody needs to know the bhajan beforehand. It gives everyone a defined moment to sing, which is far less exposing than being invited to "join in whenever". And it creates alternating waves of sound, one voice then many, which is a large part of why these evenings feel the way they do.
This is also why the room matters so much. If people cannot hear each other responding, the response dies. A room that is too large, too dead or too spread out kills participation before anyone has decided not to participate.
tempo climbs, and then it has to come down
The middle of a set generally accelerates. Bhajans get faster, clapping enters, and the room gets louder. This is the part people remember.
What is less obvious is that the climb has to be paced. Reaching the peak too early leaves half an hour of trying to sustain something unsustainable, and rooms tire faster than musicians do. A set that builds across forty minutes and peaks near the end is far more effective than one that arrives in ten.
And it has to descend. Ending on the loudest, fastest bhajan leaves a room agitated rather than settled. One slow closing piece brings everyone back down, and it is the difference between people leaving buzzing and people leaving quiet and unhurried. For most devotional gatherings, the second is what you want.
what the percussion is doing
The cajon or the dholak is not keeping time for the singers. The singers can keep time.
Percussion in this setting is doing two other jobs. It tells the room when to clap, which is the single biggest driver of participation, and it signals transitions. A tempo lift, a change of bhajan, the approach of a peak: all of it is communicated rhythmically before anything changes melodically.
Watch a room during a live set and you will see people start clapping a beat or two after a percussion cue, not after a vocal one.
why this matters for hosting
Three practical consequences.
Do not schedule anything in the middle. A speech, an announcement or prasad distribution halfway through does not pause the arc, it resets it. Whatever was built has to be built again.
Give the set enough time to have a shape. Twenty minutes is a performance. Sixty to ninety minutes is an arc, and the arc is the thing people remember.
Place it where the room is already gathering. Immediately after an aarti, the room is quiet, attentive and facing the same direction. That is the easiest opening any set can be given.