Must a valid Qur'an reading be mass-transmitted (mutawatir)?

In al-Nashr fi al-Qira'at al-Ashr, Ibn al-Jazari sets out the three pillars of a valid reading: agreement with Arabic in at least one way, agreement with one of the Uthmanic copies even potentially, and a sound chain. ¹ He then pauses on the third pillar, noting that some later scholars required mass transmission (tawatur) in it rather than a sound chain. ² See: Qur'an readings.

Ibn al-Jazari holds that his criterion is the correct one among the leading verifiers early and late, and that Abu Amr al-Dani stated it. ¹ By a sound chain he means that the reading is transmitted by upright, precise narrators from others like them back to its source, and is well known among the masters of the field. ³ He rejects the requirement of mass transmission on two grounds: if mass transmission were established, the other two pillars - the script and the rest - would be unnecessary, since what is mass-transmitted must be accepted whether or not it fits the script; and requiring it for every disputed variant would exclude many variants established from the seven imams and others. ² He says he had earlier inclined to requiring mass transmission and then saw that it was wrong. ²

Ibn al-Jazari reports that some later scholars required mass transmission in this pillar, holding that the Qur'an is established only by mass transmission and that what comes by solitary report does not establish Qur'an. ² Their names are not given in the pages read.

Ibn al-Jazari quotes Abu Shama in al-Murshid rejecting the claim, current among some later reciters, that the seven readings are all mass-transmitted in every single item reported from the seven, and holding that certainty of their revelation belongs to what all the paths of transmission from them agree on, without objection, and is well known and widespread. ²

He also quotes Ibrahim ibn Umar al-Ja'bari: the condition is one - sound transmission - and the other two follow from it. ²

The arguments of those requiring mass transmission, from their own books, and the rest of Ibn al-Jazari's discussion are not given here.