I am finishing up a 440 pump gas bracket engine now.
I plan on dyno testing a couple different cams in it versus the one I just installed. I checked the valve timing on all 3 while I had just the number1 piston in to see what I had to do to degree them in later.
With the same timing chain and crankshaft,I got three different results with three different cams.
One was perfect,the next was two degrees retarded,the last was supposed to have three degrees of advance ground into it but was five degrees Advanced.
I always check and correct . Big blocks can use multiple key way timing sets or degree bushings in the upper gear.
Small blocks have offset keys available.
Keith

The only cams I've never degreed are the ones I couldn't find the timing events for.

I had a cam gear from MOPAR Performance that had the "dot" drilled on the wrong side of the gear. I also had a custom ground roller cam from a reputable cam grinder that was off 8 degrees-retarded. I checked that one every-which-way.

So, I degree every cam and I check every lobe on the cam for opening/closing/centerline and lift.

The basics of degreeing a cam is to verify it is installed correctly, but with a few additional measurements you can check the cams duration at various lift points to get an idea of how aggressive the lobes are.
It is nice to have the data of the actual installed cam position just in case the engine has issues running correctly, it eliminates the variable that would other wise be unknown.