WASD+Shift+SPACEBAR for mobility takes up every finger on hand.
Perhaps you don’t really like to strafe jump HORSE?
Side keys on my mouse force me to re-grip the mouse.
I don’t think the speed of how quickly you need to throw a grenade is really an issue as nading is more about timing and accuracy of the throw. Whatever minimal speed advantage gained would be negated by the fact that I’d have to sacrifice mobility and accuracy.
Wolfenstein tried what Brink is proposing. Many of the comp players ended up using a script that bound a key and mouse1 to nade at the same time. So what we would do is hold down the nade key “g” (or 4 in my case) then simultaneously hold mouse1, then release the nade keyboard key, then release mouse1 to execute the throw. Needless to say it was annoying and I uninstalled Wolf as soon as the fail tourney ended.
