イッキ見って英語でなんて言うの？

In North America we call what you did "binge watching". It means you sat down and did nothing besides watch a full season of a TV show. So you can use binge watching to explain the act of sitting down and consuming a lot of one show :) Side note on 'season' v. 'series': You are using the word 'series' which in the U.K means one part (6-22 episodes of a show) in North America we would call this a 'season', where the whole run of a show is called a series (1 season or more). "I watched a full season of Friends (22 episodes) in one sitting." Is very different to, "I watched the whole series of Friends (236 episodes) in one sitting ."It is very different!

We often refer to box sets as this is a convenient way to refer to a complete series of something - previously for sale as CDs in boxes - but now the term is used for downloadable films or series available to view on smart TVs or computers or smartphones. If you do see a whole series in one sitting, then important information would also be the duration of the viewing period - as in sentence 3.

To "binge" means consume something in copious amounts. So when you say you "binge-watched"something, you're explaining that you watched something a lot (usually in one sitting). If Grey's Anatomy is a show you binge-watched, then you can say: - I binge-watched Grey's Anatomy on Saturday -I watched the whole series in one sitting.. -I was watching Grey's Anatomy on Saturday. I watched the first 3 seasons in one sitting.

the 'whole series' suggest watching it all as whole means complete/all. If you watch it all without having a break then it's called 'one sitting' you can also say 'one go' if you are describing when you watched it you can say 'one afternoon' or 'one evening'

Marathon used to express something that takes a lot of time in this instance. Example two states whole series. Meaning complete

When one is trying to express that they have watched a whole series you may simply say that you have completed the whole series in a day. This is one of the most simple and basic ways to express this. It is also common for people to use terms like 'binge-watch' or ' having a movie/series marathon'.

If you wanted to explain that you watched a whole series of a television drama at once/in one sitting, you could state one of the following, "I watched the whole series in one sitting", "I binged watched that television drama all at once" or "I watched the complete series in a day". All three of these sentences explain the act of watching a television show all at once.