kazinator parent
I can't read anything that is too far out of my fovea. If I look at a word in the middle of a sentence, I can read it, and the two immediately adjacent words. After that, the ability rapidly declines. If the next words after those two are simple like "and" and "the", I can still read them while staring at the middle word. Beyond that, I am aware that there are letters and words, but no decoding takes place. If something fits on the screen, it's nice that I don't have to scroll around, but I certainly cannot see it all at once in a semantic way, only as a picture.
It's more a matter of comfort for me than anything to fit a program in a single screen or a function with a single line - large programs and functions are significantly more anxiety-inducing for me to read and work on. I have to keep scrolling and scanning back-and-forth and easily lose my train of thought and get the feeling that I've forgotten something important.
Folding editors can help. Maybe also if there were a thumbnail of the file in a sidebar, with a rectangle representing the current viewport, that could help reduce the anxiety, by giving you an estimate of how much more is there off-screen.
Beyond that, it's part of the course. Nowadays you will not get to work on a production anything that all fits on your screen. Individual files might, but they are part of a whole that doesn't.
Self-contained programs that fit on the screen are able to do that because they reference a language, and that language is not on your screen. You learned the language and so you don't have to take your eyes off the program to look up the documentation or source code.