If your code reaches a level where you want to hide it behind regions then you have a problem that regions won’t solve. Regions are good to hide things that you don’t want to have knowledge about such as auto-generated code. Normally, when you’re developing you end up reading more code than you write it so why would you want to complicate the reading process.
I, for one, would love to have that one discussion around regions where someone convinces me that they solve a problem that has no other alternative solution, but I’m still waiting. The most frequent argument I hear about regions is that they allow you to structure your code, but why don’t just structure it using classes, methods and all that other stuff that OOP is about because at the end of the day, you should be doing object oriented programming and not region oriented programming.
Having said that, I do believe that sometimes is helpful to have a quick overview of a code file contents and Visual Studio allows you to do just that through the Collapse to Definitions command (CTRL + M, CTRL + O) which collapses the members of all types; if you like regions, you should try this, it is much more useful to read all the members of a type than all the regions inside a type.