In a number of shuls, it has become a minhag to switch Shat"z during the weekday Shacharit at these locations. I am assuming Nusach Ashkenaz in my examples:
- One person says only Birkot Hashachar -> end of Rabbi Yishma'el
- A new Shat"z from Mizmor shir Chanukat Habayit -> end of Shira (Az Yashir)
- A new shat"z from Yishtabach -> end of Tachanun (see Hallel, below). On Torah reading days, he takes out the Torah and returns it
A new shat"z from Ashrei -> end of Shacharit
On Hallel days, another shat"z says Hallel only, and the previous one (oen that did Amidah returns to say Kaddish
What is the origin of this minhag (not everyone does every item mentioned above; I am listing the full range that I have seen in a some places), and why where these specific places chosen?
Among the list, an additional question. I would think that the one that begins Psukei Dezimra should end it. I.e. - it seems to start with a bracha, Baruch She'emar and end with a bracha - Yishtabach. Why do they call a new shat"z before Yishtabach? Isn't that still part of P'sukei D'Zimra ?