IMO pros can hit their workouts with such vigor that they need that time to recover. its the whole relationship between volume, intensity, and frequency.
many times people will do more thinking they need to do more. these same people are also horrible at adjusting the intensity and volume to account for the frequency. and these variables also change with your work capacity and recovery ability which do not change in unison. to me this is where knowing the science is great but not knowing the art of exercise programming can cause you to have a subpar workout. paralysis by analysis is what some call it.
also Pros will do other work on what can be called off days. things that they may not consider a workout, like mobility work. some like jim wendler recommends will do conditioning work on non lifting days. or some powerlifters i know will do high volume low intensity active recovery stuff 3 days a week while lifting and conditioning 4 days a week so they are doing something every day but will generally only talk about a 4 day a week lifting program.
