Extracting sequences of statements into a function sometimes improves readability, when those sequences do together some recognizable operation, but other times such an extraction worsens a lot the readability, because now you need to also open other pages to see what the program really does, when the statements in a sequence are not really related.

Even in programs optimally written for readability it is frequent to have iterations or selection statements much bigger than a page, especially where the coding rules enforce a small length for program lines, e.g. 80 characters.

In languages that follow Algol 60, like Pascal, C, C++ and so on, which have a single kind of statement brackets, it is frequently needed to add comments on the final braces or "end", to avoid confusions when reading the program.

This is much more cumbersome than in the languages that follow Algol 68, e.g. Ada and bash, where there are several distinct pairs of statement brackets.

In real life you’ll have to deal mostly with code you haven’t wrote yourself.

I do occasionally have a long switch statement that doesn't lend itself to be broken up. If all the branches are simple and operate on the same conceptual level, breaking them out into separate functions that wouldn't be useful anywhere else doesn't make sense to me.

But it's definitely not a frequent enough occurrance to merit replacing closing braces with lengthy names that need to be kept in sync with their opening counterpart.

Agreed but it’s not always my own code I am reading.