It is just a minhag not a chiyuv so one has no obligation to hear every word (I asked a Rabbi not my opinion). Therefore one may got to a place that leins it fast although I agree if you cant catch most of what the baal korei is saying it may be a waste of time.
WIY: That’s his point. If it was a Chiyuv then maybe you’re Yotzei something. Since it’s just a Minhag and you’re not actually gaining any understanding from it, it borders on a waste of time.