I also generally prefer to shoot into the long dimension, having the speakers on the shorter dimension wall. However, in some cases, due to space constraints and a big, long 72, 80, or 96 input console, as a practical matter you have to orient the room the other way. It's not impossible to have a good sounding control room with this orientation, though it is more of a challenge. You need a certain amount of depth regardless of the orientation or you are going to be in trouble WRT the listening position (you don't want to be dead center) and reflections from the back wall if it's too close. With enough trapping of proper design, you can make it work, but I'd rather spend my time, money, and energy making a good room excellent than a mediocre room good.