What is the correct amount of vacumn advance?

Vacum advance only comes in at part throttle and thats why some cars have around 50 at part throttle combined with 30 to 38 total mechanical advance. But at wide open throttle you have no vacum advance so if you have a total mechanical advance of 38 thats all you will have at wide open throttle. On my street/strip cars I dont run any vacum advance because I run a quick mech advance and have the full 38 in by 2000 rpm. Ron