You should never move your hand away from movement, even a second or so is going to matter in a situation were you might be targetted by an AoE so moving your hand away from the movement keys is detrimental.
I can see this work if you play like with a controller.
But from what you've written below, you only use WASD and arrow keys for movement, how do you strafe and run backwards, if you use the standard movement you'll backpedel and strafe is bound to Q and E if you don't use your mouse?