The longest battle in manga history is Akagi's mahjong match against Washizu, which took 20 years of serialization to complete. The match begins in chapter 70, published in 1997 and concludes in chapter 296, published in 2017. That's one match that spanned a total of 226 chapters.

So if you ever wondered why the 2005-2006 anime just cuts off partway through the match, that's because they'd caught up and were more than a decade away from actually being able to finish the arc. There is a live action adaptation that ran from 2015-2018, and does cover the whole thing start-to-finish.