Q. A man has a daily schedule to daven shachris btzibur attend a daily shiur and then go to work. One morning he wakes up late. There is a later minyan he can go to but he will miss his shiur. He can daven biyichidus and still make the shiur.Showing up late to work is not an option. Is it better to miss tfilla btzibur or miss their regular shiur?
A. Igros Moishe (O.H. 2: 27) addresses the question if a Talmid Chochom is allowed to daven without a minyan, since he wants to learn late at night, and it will difficult for him to get up on the morning and daven with the tzibur. After establishing the great obligations involved in davening with a minyan, he writes that even a dedicated Talmid Chochom, who engages in constant learning and teaching of Torah, should see to organize his learning in ways that should not interfere with praying with the tzibur and thus loosing many mitzvos involved, such as reciting kaddish, kedusha, borchu etc. Adding also the erroneous example given to others, that may not be aware of the reason he does not come to minyan.
However, when occasionally a situation occurs where one is to choose between disturbing the accustomed sequence of learning an established shiur, and the cascading bitul Torah resulting, or the infrequent missing of one tefila betzibur, Poskim maintain, as can be deduced from the Remah (O.H. 90: 18) and Mishna Berura (ibid. 56), that in this particular situation there is room to choose the shiur.
Michtevei Chofetz Chaim (cited in Piskei Teshuvos 90: 23) quotes that the son of the Chofetz Chaim related how hard his father worked to put together the Mishna Berura, sometimes working over ten hours non-stop, missing sleep and meals, and occasionally missing also mincha with a minyan.
Halichos Shlomo (5: 16) quotes R.Sh.Z. Auerrbach zt’l saying that one should not interrupt the learning with a chavrussa or his Rebbe for tefila betzibur and certainly not when the teaching Torah to many is involved.
Horav Shlomo Miller’s Shlit’a opinion is similar, when it cannot be prevented and occurs only occasionally.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a