Exclusive vs Combo

How different would the training be for these two types of runners. How much of the actually training would be different, since you can’t train the 2 the same way. At least not exactly the same way. But there are things that the 2 would do that would be similar.

What are the advantages/disadvantages to being an exclusive 100m runner or exclusive 200m runner, etc. vs 100/200, or 200/400.

Would Mo or Shirvington benefit from running the 200m? Would Kederis or Little benefit from running the 100m or 400m? Would MJ have broken the 200m record if he didn’t run the 400m & vice versa?

How is it that an elite sprinter can run 9.8 but never run under 20.3 for the 200m? :o Whats the problem here?:help:

Basically,
You keep speed as the main focus in both of these type athletes. The combo would be given a bit longer distances in special endurance work and the tempo work could be increased as well.