Splitting learning for a siyum

Question

For various purposes such as the one discussed in Source for finishing the entire Mishnayos for Shloshim, people organize projects to complete some section of Torah (e.g. an order of Mishna) collectively, with each participant taking a different part, and then for the collective to make a siyum on the whole section. Are there sources discussing whether this is a legitimate practice? One might expect that a siyum would be an appropriate celebration of one large achievement in learning as opposed to a bunch of parallel small ones.

Answer 1

Rabbi Lauffer at Ohr Somayach writes:

Is It Permissible for a Few People to Learn Different Parts of the Tractate and Make a Siyum Together?

Yes, it is (see Chavot Yair 70 and Maharshal). If possible, all those who learned the tractate should endeavor to gather together and to celebrate collectively.

On the other hand, in his chapter on the Nine Days (p. 59:n.48), Rav Simcha Bunim Cohen brings a machlokes between the Kinyan Hatorah B'halacha (5:52):

and the Vayivarech Dovid (1:24):

Rabbi Cohen (5:c:i) follows Rav Dovid Harfenes and paskens in the English section of the sefer: "Meat and wine may not be served at a collective siyum; i.e., a siyum celebrated after each person of a group studied a different section of hte same sefer. Even though every word of the sefer was studied, no one individual studied the entire volume."