Rating Each Event in Terms of Difficulty to coach, each one has its own challenges. I think MD and Distance are actually pretty different in terms of every part of the approach-but then again only opinion.
Sprints:
Talent plays a larger role, you have FT muscles or you don't-often less improvement statistically from HS
Scientifically: moderately hard
Time Commitment: Moderate
Mentality: High Pressure, but easier to simulate in workouts
Injury Risk: Higher due to explosiveness
Throws
Actual Training: Technically difficult to some extent
Time Commitment: Hard
Mental Aspect: Moderate
Injury Risk: Overuse prone
Distance: 10k up
Scientifically: Easy-aerobic fitness, and mechanical efficiency baby
Time Commitment: Extremely hard
Mental Aspect: also interesting to coach
Injury Risk: You can see it coming.
Middle Distance: 800-5k
Scientifically: Hard.
Time Commitment: Hard
Mental Aspect: Hard
Injury Risk: Moderate considering the balance between energy systems and power and endurance
Jumps:
Scientifically: Moderate
Technical: Hard
Mental Aspect: Moderate
Injury Risk: Moderate, especially in doubling in sprints