The body is connected. It is not a sum of body parts slapped together. It is a total system. So, why pray tell would you "split" the body up when performing strength training. For an athlete, splitting a strength training program by body parts makes even less sense. Does an athlete use only certain body parts in competition? Hardly. There are many athletes and trainees who are always riding the overtraining train. In my opinion, injuries are a direct consequence of overtraining. The problem with separating by body parts is that this type of training taps into the most important system that governs performance -- the central nervous system. Training the body as a whole allows the WHOLE system to recover. Not some piece meal "recovery" which is absolute bro science (BS). Now, I am not saying you cannot make gains treating the body as a bunch of separate parts. I just do not think it is efficient nor optimum.
Athletes need to spend the majority of their training on skill development not spending every day in the weight room doing certain lifts/body parts. Most trainees do not have time to spend 4-5 days in the gym for hours at a time due to having busy lives with job and family responsibilities. Well, the good news is that you CAN make gains with far less training. I have trained athletes who have made great gains performing two full body workouts a week. One of them is less intense than the other that also aids in recovery.
These full body workouts should cover all the muscle groups. One exercise for chest/shoulders, one exercise for the back, and one exercise for the legs. Throw in some ab work and you have it pretty well covered. Simple and basic. Obviously you can use more than one exercise, but in reality you could pick just one and HIT it for 1-2 sets and make sure you use proper progression. An example would be bench press, chins, and squat/leg press.
I have been able to correlate some common data with respect to nervous system burnout over my years of training myself and others Performing sets of 3 or less for a length of time greater than 3-4 weeks and most will go stale. This would be a true set of 3 or less. It would not be using a sub-max weight nor would it be multiple sets adding up to 1 or 2 higher rep sets (e.g., 10 sets of 2). This "peak" such as that used by powerlifters cannot be held by a natural athlete/lifter without going backward or the nervous system rebelling and the perceived result being "getting weaker". The lifter will feel her "snap" so to speak leave them. Or, they will get injured or leave themselves open to injury. Then, when returning to normal rep ranges what typically happens is EXTREME muscle soreness even with a moderate rep count increase. I experienced it and those I have trained experience it so a "ramp up" in rep range is needed.
The human body is not a sum of separate parts. It is a total system. Treat it like one in all respects.