The programs are effective, I enjoy them myself. That'd be silly, and kind of narcissistic. Shaun T's not going to workout to his own videos exclusively for the rest of his life. I'm willing to bet he spends A LOT more time lifting heavy than the frantic pace of LIIFT4 allows.
Meaning that he does his own blend of weights and HIIT work at the gym, and just condensed it to a BOD format. Even Joel says he created LIIFT4 as a 'version' of his personal workout style.
I mean, how did they get fit themselves before creating their signature programs? They lifted weights, did classic cardio, and ate perfect nutrition. Shaun T is clearly lifting weights regularly, and does Autumn when she wants to lean out for a photoshoot. I believe Shaun and Autumn do their own workouts from time to time when they say they do, but let's be real, that's not literally all they're doing. That's just being smart and savvy business partners. They're PROMOTING their own workouts on social media.