The idea that halachically one must always learn unless faced with an emergency is a daas yuchid. The Ran paskens so, however, Ridvaz in Tshuvos chelek gimmel, #416, points out that virtually all Rishonim disagree. Rashi, Rosh, Ritva, Rashba, Rabbeinu Yonah, Sefer Hayirayim, all paskin that you are mekayim the Cheyuv of learning with Krias Shma Shacharis V’Arvis. Anything more is a reshus and a mitzvah b’alma. This is according to Stama D’gmarah in Brochus 35b.
Also, see the Ohr Samaich in Hilchos T”t. I paraphrase: “….. How could Hashem establish a choiv of Talmud Torah for everyone (we are all different)? Therefore, the Chachamim explained the true nature of this cheyiv (Talmud Torah) as follows: Krias Shma Shacharis V’arvis is a fulfillment of the passuk of Vhigesa Boi Yoimam V’layla……. & I am not satisfied with th Ran’s explanation……….”
Of course, there is always the inyan of learning Torah, but again, that is a crucial inyan but not a cheyiv.