Q. Some people have developed a custom to eat only “shmura” matza the entire Pesach. Is there a basis for such a minhag considering even our “non shmura” is generally watched in a fashion that technically would have been considered shmura to be yotzay the mitzvah of matza m’ikar hadin?
A. Shulchan Aruch (O.H. 475: 7) rules that the obligation to eat matza is only on the first night (and Rabbinically also on the second night in chutz laaretz). Mishna Berura (ibid. 44) mentions in the name of the Gr’a that although there is no obligation to eat matza during the rest of Pesach, if one does eat he complies with the mitzva of eating matza. Others also agree such as the Rokeach (291), Chezkuni and Eben Ezra (Mispotim 23: 15), Chasam Sofer (191) mentions that so is the opinion of the Rosh and the Ran, et. al. Avnei Nezer (377) and Gilyonei Hashas (Pesachim 38a) compare it to seating on the suka on the rest of the Yom Tov.
Since one complies with the mitzva of eating matza, according to the above Poskim even on the rest of the days, it is advisable that proper Shemura Matza as the one used at the seder, should be also used.
Horav Shlomo Miller’s Shlit’a opinion is that one should follow the established mihagim of one’s family. The Rov added that Horav Aharon Kotler zt’l would eat matza shemura during the entire Yom Tov, excepting when he ate kneidlach.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a