Our Gemara on amud beis discusses a conceptual difference between something that is gifted versus bequeathed:

If a person on his deathbed said: My property is given to you, and after you to so-and-so, and the first recipient was fit to inherit from him, the second gets nothing in place of the first. That is, he does not receive the property after the first one dies, as this formulation employed by the owner was not one of a gift, but a formulation of inheritance, and inheritance has no end, i.e., it cannot be stopped. Therefore, since the first recipient acquired it as inheritance, his heirs inherit it from him, and it cannot be taken by the second one.

This Talmudic principle that "inheritance has no end" is expressed in the original Hebrew as, "Yerusha ein lo Hefsek," which can also be translated as, "inheritance has no interruption." The Mei HaShiloach (Volume II, Devarim, Shoftim) applies this via a play on words to a verse in Devarim (16:20):

Justice, justice shall you pursue, that you may thrive and occupy the land that Hashem, your God, is giving you.

What does the pursuit of justice have to do with inheriting the land of Israel? The Mei HaShiloach explains that the true inheritance here is the Torah (as stated in Devarim 33:4). The Hebrew word for justice, tzedek, can also be translated as "correct," "proper," or even "justified," as in understanding the justification behind something. Therefore, he reads the verse as follows: “[If you do not understand a part of the Torah], pursue and pursue relentlessly until you understand it, and then you will come to the inheritance.” This is not a gift that can be interrupted, but an inheritance that will eventually lead to a full grasp of the subject matter.

In yeshiva, the idea of studying Torah be-iyun—in-depth—is highly emphasized. This is certainly important, as seen, for example, in what the Baal HaTanya says in Tanya, Part IV, Iggeres HaKodesh 26:24. Yet, the idea of be-iyun taught in yeshiva is not limited to the analysis of Rabbenu Chaim and the like. While the yeshivishe lomdus (analytical methodology) is often breathtaking in its depth and sharpness, it does not monopolize the definition of studying be-iyun.

The true definition of be-iyun aligns more closely with Mei HaShiloach's description. It is a simple and sincere effort to understand what you are learning with as much depth as possible. A good acharon can indeed help you understand a Gemara, Rashi, or Tosafos better, but you can also continue pondering it until you feel that you grasp it. In fact, pondering a pasuk in the Torah to uncover its depth is arguably just as valuable, though it’s important to stay grounded in the Gemara and traditional commentaries to avoid being led astray with ideas that are too fanciful to represent Torah ethos and creed.

Brisker analysis and other schools of lomdus are just one way to understand Torah in depth. Ultimately, the method is less important than the pursuit and the discovery, however they are accomplished.