"That also is difficult."

Akṣayānanda Swami: Of course we accept, ah, when you tell us to chant sixteen rounds, we accept that figure as being, in perfect faith, that you're the ācārya, but ah, what if others we wanted to convince, is there any, any ah, śāstr... Is there any Vedic verse we can refer to to corroborate that at least they must chant sixteen rounds. Or that many number of names?
Prabhupāda: No. In the śāstra it is not said like that...
Akṣayānanda Swami: I see.
Prabhupāda: It is said, śaṅkhy-pūrvakaḥ...
Akṣayānanda Swami: Śaṅkhy-pūrvakaḥ.
Prabhupāda: You must fix up.
Akṣayānanda Swami: Counting.
Prabhupāda: You must fix up in numerical strength.
Akṣayānanda Swami: I see.
Prabhupāda: Whatever you can.
Akṣayānanda Swami: Yes.
Prabhupāda: But I have fixed up sixteen rounds, because you cannot do.
Akṣayānanda Swami: That's all we can do.
Prabhupāda: (smiling, touch of irony) Yes. That also is difficult.
Akṣayānanda Swami: Yes. (laughing)
Prabhupāda: Otherwise, Haridāsa Ṭhākura was chanting 300,000. So, That is not possible. You should not imitate, but whatever you fix up you must do.
Akṣayānanda Swami: Yes. Yes.
Prabhupāda: That is wanted.
Akṣayānanda Swami: Yes. I was told in the beginning you asked the first disciples to chant 64 rounds?
Prabhupāda: Yes. I asked them to chant 32?
Prabhupāda: (grinning) Hm.
Akṣayānanda Swami: Is that correct?
Prabhupāda: Śaṅkhy-pūrvaka nāma-gaṇa-natibhiḥ. Śaṅkhya purva, or numerical strength must be there. And you should follow rigidly.
Akṣayānanda Swami: So if, if we are serious and sincere, it means that that sixteen will increase to, ah, to continuously chanting.
Prabhupāda: You can do also now. It's not that because I've finished sixteen rounds...
Akṣayānanda Swami: No.
Prabhupāda: You can increase. But that sixteen must be finished.
Akṣayānanda Swami: Yes. (pause) What I mean is, that's to bring us to the platform of chanting constantly. That at least we do that numerical number, finally we may be able to do, if we're fortunate to chant constantly day and night.
Prabhupāda: Yes.

 Morning Walk -- December 11, 1975, Vṛndāvana