Upon further consideration, however, Rav Ahai Gaon appears to be perfectly correct, since there is actually more to the Sugya than we have heretofore seen:
The Poskim accept the view of רב חסדא ורבה בר רב הונא against that of רבה, so Rav Ahai Gaon’s requirement of day and night care seems eminently logical, and Rav Berlin’s objection quite baffling. This point is made by Neziv in his העמק שאלה :
[Although he does not mention Rav Berlin’s comment, he clearly intends to rebut it. Neziv notes in an introduction to העמק שאלה that he will generally not make explicit reference to the משמרת שלום where he dissents from it, and explains why: