Quote Originally Posted by al Roumi View Post
(i've not used any yet but I doubt they have fire by rank or other drills).
There is fire by rank available when you're standing still, so best depth for teppo units is probably 2-4 lines depending on the battlefield.
I don't think there is one optimal depth for other units, cavalry will probably smash through any unit that is stretched too thin even without wedge formation.
I use rather thin lines because I've never ran into a situation where I'd be critically out of space, where deep lines would be more beneficial or where I was at risk of being charged by cavalry.

I suppose it depends mostly on your style of play.