Question

There is reliable testimony (videos, or from Rabbi Nachum Yavrov, who was an important and trustworthy halakhic decisor) that Rabbi Elyashiv would study “only” Talmudic text. In other words, he would review the Talmud in front of him many times, he knew the back-and-forth of the discussion thoroughly, and people did not often see him opening books by later authorities (Acharonim). And nevertheless, he was familiar with them and discussed them like someone who had studied them extensively. I heard an explanation of this from Rabbi Yisrael Landa (rosh yeshiva of Heikhal Yitzhak, author of Pituhei Hotam, close to that kind of Schreiber style): he said that when you really know the Talmud, then studying the later authorities is much easier, clearer, and faster. For example, you open a responsa of Rabbi Akiva Eiger, he brings one Talmudic passage, fine, then oof, a second Talmudic passage, already hard to keep track of, then he brings Tosafot and another Talmudic passage and you’ve completely lost him. That would not happen if you knew Gemara, Rashi, Tosafot thoroughly.
 
Is that something you agree with? In other words, is there really an important emphasis on studying Gemara, Rashi, and Tosafot in depth and knowing them almost by heart (at least in the passage we are currently studying), and only then studying the later authorities, their line of reasoning, insights, and so on?