Have you ever tried a professional, straight-razor shave? Aside from feeling wonderful, that usually leaves me without a shadow for much longer than just shaving myself.
I always shave normally once, and then go back and shave against the grain for a 2nd time. It takes longer, and the 2nd time doesn’t feel as “effective” but it def. works. You just keep feeling your face, and if you feel any stubble, just shave against it in that area. It takes some time, as it’s doubling or tripling your shave times, but it’s quite effective in creating REALLY soft skin for a bit longer time.