I use to always check the lobe separation angle at the retainers, same on verifying cam timing until one of the racer reps at Comp said that is not the way they want you to check the cam lobes due to rocker arm ratio affecting the cam timing, which it does
I now check the cam timing on the lifters (and adjust the cam timing as needed) and verify the cam advance on the lobe centers by verifying the intake lobe center first and then both of them after I get the intake lobe where I want it by checking them at the retainers and then verifying the exhaust lobe separation angle to make sure the lobe separation angle is ground correctly on every cam If the cam is ground on a 108 LSA and it is installed at 4 degrees advance so the intake lobe center is at 104 degree after top dead center the exhaust lobe max lift, lobe center, should be at 112 degrees BTDC If it isn't like that the cam LSA is ground wrong.
I've had several custom ground "racing" cam that where not ground on the LSA that was on the cam card
I also check the LSA at .050, .100 and .200 before and after max lift on all the lobes I check If the lobes are within one degree of each other at all three checking LSA heights I use that cam
You can't be to careful