I just built an addition on my house, and I staggered the sheathing on the gable end to cover the joint between the walls and trusses. I was always told this helps strengthen and tie them together.
I would recommend it, but not sure if it is absolutely necessary.
Just wanted to say hello from the snowy abyss, CNY. Great info on here and will surely be asking questions and looking for ideas when I start on the 20 x 24 first, and then on to my 16 x 20 that will be mostly storage.