As a simple example of that, using a dumb text editor like notepad as the baseline, changing the same 10 characters on 10 consecutive lines will take at least 200 keystrokes (100 DELs, 100 times typing the same characters back in, plus the movement keys - about 9 to move down to the next row.
With a bit of thought, in notepad, you can reduce this a bit. use Ctrl-C and Ctrl-V to reduce the amount of typing - but you'll still need to either DEL or select the words to replace, in the same location on each line.
With a more modern text editor, you can select a rectangular area and replace the text within it. In vi, replacing those 10 strings on 10 consecutive lines will take (starting at the first character to replace, like Notepad, and assuming it's a single word inside separators):
Ctrl-V e 1 0 j c A_NEW_WORD
That's 16 keystroke instead of over 200, with no mouse movements.
This is something I do frequently enough that I didn't need to even think for a millisecond to bring to mind the keystrokes needed to do it.
Now, I'm not arguing your editing style isn't different - maybe you've never needed to do this - but I would argue that this is a fairly common programming text editing task.