It's an interesting thought! Boredom can definitely lead to study fatigue, but the people in this example were medical students preparing for a high-stakes board exam at a top-10 institution. Boredom might be less of an issue at this level - it's more about efficiency and a tremendous feeling of stress and pressure. Indeed, several of these students who were in danger of failing were studying as much as 10-12 hours per day... essentially spinning their wheels in the mud.

That being said, combatting boredom is a really important thing to consider.