well some of the cam grinder do not have machines that good ?? or for $250 they will spend only so much time on this .like i said on stock rerings i do not. but on something that has a new cam i do .but i have seen them by off 2 degrees this dose not keep me up at nigth less you want to buy a cam grinder and start grinding them your self .this is something to all ways check but there is some stuff that i will spend alot more time on and the chain will stretch and move it any way with a new crank and timming set i will check them every time