We can always say the Name of Amida Buddha

Question: If it is said that it does not matter how many times we recite Nembutsu then why does Shinran urges us to say it constantly in this hymn:

“Those who deeply entrust themselves
To Amida’s Vow of great compassion
Should all say Namo Amida Butsu constantly,
Whether they are waking or sleeping.”

Answer: Shinran also said:

"In the Primal Vow are the words:
'Saying my Name perhaps even ten times'.

Know from the words 'ten times' that appear from the beginning in the Vow itself that saying the Name is not limited to one utterance. And the word 'perhaps even' makes it clearer still that there is no set number of times one should say the Name." (Notes on Once-Calling and Many-Calling)

"'Saying my Name perhaps even ten times': In encouraging us to say the Name that embodies the Vow, the Tathagata added 'perhaps even' to the words 'ten times' to show that there is no set number of times the Name must be said, and to teach sentient beings that there is no determined hour or occasion for saying it. Since we have been given this Vow by the Tathagata, we can take any occasion in daily life for saying the Name and need not wait to recite it at the very end of life." (Notes on the Inscriptions on Sacred Scrolls)

Honen Shonin also said:

"Question: Which is superior in merit: a mere single utterance of nembutsu or ten repetitions of nembutsu?

Answer: They have the same merit with regard to birth in the Pure Land.

[...] The number of recitations is not the issue. The merit of birth in the Pure Land is equal, as is clearly stated in the Primal Vow. How can there be any doubt?"

The above passages show that the verses “should all say Namo Amida Butsu constantly, whether they are waking or sleeping” were actually an urge by Shinran to not forget Amida’s benevolence in our daily lives, and NOT that if we do not say Nembutsu day and night or when we are asleep we are not saved. The Primal Vow is clear: “saying my Name perhaps even ten times”, so Amida did not emphasized the number of Nembutsu recitations. Shinran, who could not contradict Amida Buddha himself, actually wanted to show to us that we can remember Amida’s compassion anytime, without regard to time (day or night/awake or asleep) and circumstance which - “we can take any occasion in daily life for saying the Name”; „there is no determined hour or occasion for saying it.”

The Nembutsu of faith can be said anytime, even in the dream when we are asleep (I myself say it in the dream from time to time) or during ANY daily activity.