Yeah that's it mate, cam manufacturers decided to specify the duration @ 0.05" lift, however this isn't the peak duration of the cam, its just a helping hand in dialing the cams in. I see so many people choosing such wild cams like 280 degree's duration which just make them real lumpy and no bottom end power, when they could just opt to use a cam with a different LSA. Running a wide LSA gives a decrease in overlap making the cam much smoother and improved low-mid range, but limits top end power no matter how much duration of lift you have. Go the opposite way with a tight LSA the overlap increases meaning you loose bottom end torque, gives lumpy running but provides much better top end. The stock inlet cam has an LSA of 110 degree's, exhaust is 112 degree's. Ivan Tighe billet cam's have an LSA of 114 degree's, as you can see here the LSA is widened for aftermarket billet cams to provide smooth running with increased duration.