Question: May one interrupt while reading Shnayim Mikra?
Answer: The Alter Rebbe states that some are accustomed to read the entire week’ s Shnayim Mikra without interruption at all, but that according to the basic Halacha, one may interrupt it and read “one Parsha today . . and another Parsha tomorrow”. [In this context, Parsha refers to a segment of Pesukim in the Torah that appears without any space between the Pesukim, also known as “Pesuchois” and “Stumois”.]
This implies that if one does not wish to read the entire week’s Shnayim Mikra at once, he may interrupt only when there is a break in the Torah between Parshiyos.
From this it can be inferred that:
1. It is ideal to read the entire week’s Shnayim Mikra without interruption at all.
2. It is acceptable to pause when there is a break in the Torah between Parshiyos.
3. One should not interrupt within a Parsha at all.
Although point 3 is only implicit in the Alter Rebbe, the Mishna Brura (Shaar Hatziyon 285:11) states this explicitly.
It should be noted that obviously where necessary one may interrupt.