Cam degreeing. I totally don't understand.

Say you put it together without putting a degree wheel on it. Start it and somethings off. You go through all the easy external things and you sit and stare at it, cursing yourself because you don’t really KNOW and you know what a PITA it is to pull the cover. It’s probably going to leak oil after! You are pulling your hair out!!!! Nope, not me, trust but verify. A friend of mine bought a hemi crank that had the keyway cut in the wrong place. The manufacturer was very leering of selling it, they had a number of them. but as long as you know. Not hard to overcome. Fast forward 10 years and two owners later? That can be a nightmare.