A) Both hands on the keyboard, making it easy to reach both the Win key and the arrow keys at the same time to snap your windows.
or
B) One hand on the keyboard and one hand on the mouse, making window snapping instant with the mouse.
But I forgot that this is HN, so a significant proportion of readers also use their computers with both hands on the mouse, or no hands and one foot each for the keyboard and for the mouse.
Edit: Sorry for being sarcastic.
> A) Both hands on the keyboard, making it easy to reach both the Win key and the arrow keys at the same time to snap your windows.
It might be "easy" to reach arrow keys, but it's even easier and faster not having to do that
> B) making window snapping instant with the mouse
Your left window slightly overlaps the right one. You want to resize it by reducing its width by ~5% and its height by ~9% to avoid that Name your "instant" list of mouse actions to achieve that.