[pistacchioso]

I think vi speed is much more theoretical than practical. v5j to select the 5 lines below? Sure, I can't think of a faster mode. BUT in reality

1. you have to check if you're in insert mode or not. Or you think you are, you're not, write vf5, press esc, press u to undo, retype vf5. Or you don't know and you press esc before it, so it's actually esc+v5j, and esc is not the easiest reachable key

2. you have to know you want to go down 5 lines. In reality, you know you want to go "a bit" down, so in a real world situation you either count (slow), make a subtraction with line numbers (slow) try to guess a number of lines, check what you've reached, keep retyping. This is all but "cognitive free". What is cognitive free (although requires more keystroke) is just press shift+down+down+down+down+down, for me.

[_pius]

I see your perspective, but I disagree that vi speed is mostly theoretical.

1. you have to check if you're in insert mode or not.

You should always be in normal mode unless you're actively inserting, so this shouldn't be something you really have to think about.

2. you have to know you want to go down 5 lines....

Since your example assumes that line numbers are visible, you could just type vnG, where n is the line number you're trying to put the cursor before. No subtraction needed. Depending of the shape of the text, there are probably other intuitive approaches as well.

Does the "tao" of vi take time to internalize? Sure. But once you've done that, you can be blazing fast.

[vec]

There's nothing wrong with typing Vjjjjj until it looks right, and you can still click and drag if that's what seems easiest to you. But if you're thinking of it in lines and characters you're missing the real advantage.

You're still mentally translating a what into a how. You almost certainly don't want to highlight 5 lines down for its own sake, you probably want to highlight, say, the body of a function. Vim provides a command to just do that directly.

[hexasquid]

2 - That's where relative line numbers come in.