Why is it not important how they studied? I think it makes sense to say that if the amoraim studied in a certain way, they probably knew what they were doing (because they were closer to Sinai and to the method of study that is called for), and that this method is probably the most correct one. Why should we invent complicated methods? To satisfy our intellectual cravings? Personally, I would trust the way the amoraim studied more than the style of study in the yeshivot in Europe.

Precisely in the Jerusalem Talmud, the statements that are brought are very important for defining the concepts. True, there are no sprawling discussions there like in the Babylonian Talmud, but the meaning of the citations shows deep analysis. I learned this in the introduction to “Measures for the Study of Jewish Law,” in the chapter on the Babylonian Talmud and the Jerusalem Talmud.

I highly recommend the Maharik’s responsum on this matter. Responsum 84—it is recommended to look at it inside, in context. It is a responsum with very important historical analysis.
I am copying the section relevant to the style of study:

“And if you would say that, then even before Abaye and Rava the law too should follow the words of the later student and not those of the earlier master. So why did the Geonim rule in accordance with the student only from Abaye and Rava onward? Because until Abaye and Rava, the students would study only according to the tradition of their teachers, according to what was taught to them. Some would study according to Rabbi Hiyya and Rabbi Oshaya, some according to the Mishnah of bar Kappara, or the teachings of the school of Levi, or the teachings of the school of Shmuel, and so all of them. Therefore it is fitting to rule according to the words of the master, since the student knew only what was within his teacher’s words. When the words of the master and the words of the student conflict, whose words should we heed? But from Abaye and Rava onward, they studied all the views—that is, the Mishnah of Rabbi Hiyya and Rabbi Oshaya, and bar Kappara, etc.—and therefore it is fitting to rule according to the words of the student, because he is later. For sometimes the master follows one line of the baraitot, such as the Mishnah of Rabbi Hiyya and Rabbi Oshaya, while the later authority is compelled by another baraita, such as the Mishnah of bar Kappara or the others, to conclude that the law is not so—or the reverse. Or sometimes the master did not examine one of these teachings, while the student did examine it and infer from it against his teacher’s view, as we find in many places in the Talmud, where Rav Hisda said to Rava: ‘Go out and examine it, for by evening he will ask me about it,’ etc. And further, in tractate Ta’anit (24a), ‘Rava decreed a fast…’ up to ‘If it is because of study, in the years of Rav Yehuda all their study was in Nezikin…’ up to ‘and when Rav Yehuda came to Okatzin he said: I see here the discussions of Rav and Shmuel, whereas we study thirteen versions in tractate Okatzin.’ And Rashi explained there as follows: ‘Thirteen versions—among us there are thirteen forms of study in the Mishnah and baraita of tractate Okatzin, such as the Mishnah of Rabbi Hiyya and Rabbi Oshaya, and bar Kappara, and the Mishnah of Karna and Levi, and the tanna of the school of Shmuel. And so we say in tractate Nedarim: Rabbi taught a law in thirteen ways,’ end of Rashi’s words. And it seems that in the days of Abaye and Rava they studied all those thirteen versions, which they did not do in the earlier generations, that is, Rav Yehuda and the like, since it says ‘and we study thirteen versions,’ implying specifically we, and not they, as is evident from the whole passage there. And know that this is indeed so, for in the days of Abaye and Rava the wisdom of the Talmud expanded, as we find in Bava Batra, chapter Yesh Nohalin (Bava Batra 134a), and likewise in the second chapter of Sukkah (28a), where it speaks at length of the wisdom of Rabban Yohanan ben Zakkai, that he omitted neither Scripture, nor Mishnah, nor Talmud, etc., and it lists many things there, and finally ‘the discussions of Abaye and Rava’—but not those of the earlier amoraim before them, even though some of them were greater, such as Rav and Shmuel and Rabbi Yohanan. Rather, this must be for the reason I explained: that Abaye and Rava began to study all the baraitot and sat and resolved them all so that one would not contradict another, and from this they derived many laws and established many teachings clearly and truthfully. And so too did all those who came after them, from generation to generation, and this is as I explained. Therefore the Geonim established that the law follows the words of the Talmud, because it is the latest—from Abaye and Rava and onward—and not from before them.”