I'd say most of them don't have routines at all, or the one's I've seen are pretty useless.
If you're not doing deadlifts/squats you're just wasting your time. Those 2 exercises basically work your entire body and will provide skeletal stability. Your shitty knees and back will thank you.
Add a couple sets of bench press and back exercises to thicken up your upper body. That's it.
All the crunches in the world ain't getting rid of no gut if you got one, ab workouts are a myth, that's why nobody has fat legs and arms but has a 6 pack. It's all body fat so count your calories.
Do this stuff 3x a week... Profit.