פירוש על ברכות 61:18

AND FIND HIM IN ANOTHER CORNER. The Gemara says that when R’ Akeevo prayed privately, if you left him in one corner of the room at the end of his prayers you found him in the other corner. Why? He bowed and prostrated himself many times during his prayer. Tosfos searches for the Halachic basis for so excessive bowing and prostrating. This is bewildering, for the Gemara says later (34a) that one who comes to bow at the end of each and every b’rochoh as an expression of his piety and submissiveness to Hashem, we teach him that he should not bow, because the Rabanan instituted bowing only at the beginning and end of the first b’rachoh and at the beginning and end of Modim. If so, how did R’ Akeevos bow so excessively. And Horav Yosaif answered that here referring to R’ Akeevo’s bowing we are speaking of the pleas he was saying after the eighteen b’rochos. After one concludes the regular eighteen b’rochos he may plea to Hashem for whatever else he needs and during those pleas he may bow and prostate himself even excessively.
Tosfos is not satisfied with this explanation. And this answer is not clear, for it seems that his that his excessive bowing took place during the eighteen b’rochos. And it appears to R’I that it is certainly forbidden to bow at the end of each b’rochoh, but in the middle of the b’rocho it is permissible to bow. And that is what the Gemara is discussing here in the story about R’ Akeevo. He bowed excessively during the middle section of each and every b’rochoh And when he reached the conclusion of each b’rochoh, he straightened himself for the conclusion of the b’rochoh.
And it is for this reason that it has become the universal custom on Rosh Hashonoh and Yom Kipur that when they pray זכרנו and ובכן תן and ותמלוך, they bow when they reach the verses and at the end of each b’rochoh they straighten themselves for one is not allowed to bow at the conclusion of a b’rochoh, only where the Rabanan instituted that one must bow there. Otherwise it is prohibited.

See p. 194 n. 4.

By detaining them. They would not resume the Service until the Rabbi had finished his Tefillah, and some of them might want to hurry away to their work.