Living in a border region nearly everyone here uses "manual carrier search" (I don't know the proper English term for this). Otherwise it can get pretty costly.
But isn't it tedious to have to manually change your carrier every time you cross the border? Especially when driving, I really wouldn't want to navigate these menus while on the highway.
Well - if I am staying in "my country" I leave my manual selected carrier on. When I'm travelling into the other countries I change it to automatic carrier search. Works fine for me.
I guess you have to pick your battles. Either do it manually and not worry about a big bill or do it automatically and accept you might get a big bill. How much is the convenience worth?
Well, for now I can easily do it automatically and check which network I'm on before using data-intensive apps, so I get the best of the two worlds.
I'm just interested on whether it is easy to see as well on an iPhone X.