Depends on genetics.
If you train a body part to failure and are stronger the next time, I'd say it worked. Otherwise, you just walked away with a pump and lots of lactic acid. Tons of people either overtrain or use way more weight than they can safely control. Is there really any chance doing partial squats with 585 on a Smith machine will grow muscle?
I'd say having a plan (diet and exercise) and changing workouts occasionally are the way to go.
After genetics, I'd argue most of how people look has to do with their diet and habits (alcohol, rest, hydration, drugs, etc...) between workouts.