DV is more talking about LSA which is a different matter to ICL. DV's formula indicates the starting point for the LSA for best torque across the RPM range. This uses the displacement of one cylinder and the effective valve seat diameter (intake valve diameter × 0.91). ICL is a matter of whether the cam is installed straight up, advanced or retarded.
David disagrees with those that arbitraily assign an IVC point. Use DV's formula for inline valve heads to get the LSA correct and then adjust duration to determine overlap which controls idle quality. For high CR and fast off the seat valve action the LSA is adjusted a bit. DV has a newer video out that shows the differences between LSA's of 104°, 106°, 108°, 110° and 112°, on one engine. As his video demonstrates, chosing a cam with the LSA a degree or two tight will lose a bit of torque, but chosing the LSA a degree or two wider loses more torque. And this is across the power band.
I bought a hydraulic cam from Engle to install in a 351W. Short duration for mileage. I figured I wanted a 112° LSA because that is what all the "smart guys" were saying. The cam tech sent it ground on a 109° LSA and told me it would have better torque. It ran real nicely. When I sold the car, a friend talked the buyer into rebuilding it to install in a 1948 Mercury 1/2ton. I drilled a 2 × 4 to put the lifters in to keep in order and kept the cam. I will install it in my 289 using LS 1.9" intake valves. Formula says to use 107° LSA but with 11.5:1 CR and 1.72:1 Scorpion rockers, the ajustment should be close to 108° to 108.5°. Close, and I save on the costs of a cam and lifters.