For those who think they "have" to have a dual-pattern cam I suggest reading Isky's tech article about dual-pattern cams, if it is still on their website.

There are applications for both types of cams, as well as the dual-pattern with the longer duration on the intake side. If the engine has an efficient exhaust port and exhaust system then the longer exhaust duration may be wasting power. This was discovered by some Mopar dirt-trackers when the 308 heads came out.

R.