I don't and I can give you great example of why. I built a 454 Chevy for a guy years ago. I used a Comp billet set on a Comp solid flat tappet. I put the wheel on it. Came up 12 degrees retarded. TWELVE. The number after eleven and before thirteen. TWELVE. That's been about 25 years ago and I still have a hard time believing it. But it was right. I duplicated it five or six times. It took an offset bushing in the cam sprocket along with the nine keyway crank gear to get it right, but I did and it ran like the dung who flung. That right there taught me to check them all and if somebody doesn't want to pay me to do it, I'll load their junk on their truck.