Why chant a set number of mantras daily?
“Since Your two hands will always be engaged in chanting and counting the holy names, how will You be able to carry the waterpot and external garments?
From this verse it is clear that Chaitanya Mahaprabhu was chanting the holy names a fixed number of times daily. The Goswamis used to follow in the footsteps of Sri Caitanya Mahaprabhu, and Haridasa Thakura also followed this principle.
Concerning the Goswamis—Srila Rupa Goswami, Srila Sanatana Goswami, Srila Raghunatha Bhatta Goswami, Srila Jiva Goswami, Srila Gopala Bhatta Goswami and Srila Raghunatha dasa Goswami—Shrinivasa Acharya confirms, sankhya-purvaka-nama-gana-natibhih (Sad-gosvamy-astaka 6)
In addition to other duties, Sri Chaitanya Mahaprabhu introduced the system of chanting the holy name of the Lord a fixed number of times daily, as confirmed in this verse (tomara dui hasta baddha nama-ganane). Chaitanya Mahaprabhu used to count on His fingers. While one hand was engaged in chanting, the other hand kept the number of rounds. This is corroborated in the Chaitanya-candramrita and also in Srila Rupa Goswami’s Stava-mala:
badhnan prema-bhara-prakampita-karo granthin kati-dorakaih
sankhyatum nija-loka-mangala-hare-krishneti namnam japan
hare krishnety ucchaih sphurita-rasano nama-ganana-
Therefore devotees in the line of Sri Chaitanya Mahaprabhu must chant at least sixteen rounds daily, and this is the number prescribed by the International Society for Krishna Consciousness. Haridasa Thakura daily chanted 300,000 names. Sixteen rounds is about 28,000 names. There is no need to imitate Haridasa Thakura or the other Goswamis, but chanting the holy name a fixed number of times daily is essential for every devotee.