I find it quite a bit faster to type ci] or ci) to replace everything inside a pair of [] or () than selecting the same text through other means. There are similar shortcuts for working at the word, block or "rest of the file" levels and it's all consistent across replacing, deleting and copying actions.
> I don’t have to plan ahead how many times to press an arrow
Usually, I'll just do something, e.g., hit dd to delete a line and then even though I could hit "3." to delete three more lines, I'd usually just repeatedly tap . to repeat that dd action. It doesn't really matter if the action is deleting a line or commenting/uncommenting it or changing capitalization or modifying a word in a certain way. The general strategy of doing the action you want and then repeating with . it is very useful.
