On the drive down to Texas I explained to the children how to best utilize their cellular data to stay under their 10GB (shared) plan, which revolved around exploiting wi-fi, and basic cellular do's and don'ts: Do watch a YouTube video your friend sends you over 4G, do not watch an entire series. Do listen to a song over 4G, do not listen to you entire Spotify playlist. I told them we would see how much, on average, they used the week they were gone and we would revisit.
I dropped my son at his friend's house, and my daughter at her friend's house for the week. One of those parents had wi-fi, and the other did not. My son presumed three full-length feature films on Netflix and a shit-ton of of individual YouTube videos (but quite literally not an entire season of any one thing) was permissible, as well as only listening to his Spotify at night, while he slept.
By the end of the week my daughter had used 1.9GB, and my son 10.3GB.
My daughter was decidedly not pleased when I turned off her cellular data as well until the counter reset - she gave her brother a stern talking to about personal responsibility, and how it can affect other people.