The Brisker Rov Doesn't Know About Shema, But Knows About Closing A Gemara
The Shulchan Aruch says that if a person does not say Krias Shema right before sunrise, he must still say it as early as possible and not wait until the Shiur.
Rav Michel Shurkin (Meged Givos Olam 2:3) tells a story that he heard from Rav Moshe Shmuel Shapira about someone who came to the Brisker Rov and told him that he has a chavrusa ( a fixed sesion of learning)(before davening. He wanted to know if he may learn then or he must daven right away in order to say Shema as close to Netz HaChama as possible.
The Brisker Rov aswered that he did not know the answer to his question. However he said "since there exists a possibility of doubt, the general rule that I suggest that one should follow is one never closes his gemara if there is the slightest doubt in the world that he must do so."