What holds USAC back is they try to cater their drivers to run all 3 series. You never see the sprint series running the same night as midgets. Look at all the open weekends the sprint cars have which has led to local tracks getting the USAC stars at a local price if that driver doesn't have a midget or silver crown ride. The Woo and HL focus on 1 series and build a schedule for it and have large series sponsors that only support 1 series.