Hi Raabi Gut Voch, I wanted to know if one misses some of the parshiot with shnayim mikra and cannot make them up is it still a mitsva to continue reading shnayim mikra, ie. is each parasha a misva by itself or is it only a mitza when finishing the entire 5 sefarim of humash? thank you!
While the mitzva is to complete the entire Torah once a year, there is also an individual mitzva to complete each Parsha, each week. So whatever could be completed should be, even if the entire Torah will not be completed.
The Rishonim [to Berachos 8a and on the Rambam] have varying explanations as to the reason and concept behind this mitzva. While some hold the point is to complete the Torah yearly [Rabeinu Simcha brought in Hagahos Maimonyos]. Others explain the idea is to be fluent in the Parsha being read that week [Rabeinu Chananel and the Aruch]. The plain reading of Shulchan Aruch O:C 285:1 implies that there is an obligation each week to complete the Parsha independent of completing the entire Torah.