The best application for any cutting tool follows from the material it is made of. Cemented carbide is far harder than high-speed steel and, crucially, keeps that hardness and a keen edge even when the cutting zone gets very hot.

Because it resists heat and wear, a carbide drill can be run at much higher cutting speeds and can machine tough, hard, abrasive metals that would rapidly blunt or soften an HSS drill.

So the situation that truly exploits carbide's properties is high-speed machining of tough materials, where both speed and material hardness are demanding.

Drilling wood needs only a cheap, sharp tool; carbide's expensive heat resistance is wasted and unnecessary there.

Manual metal bending is a forming operation that involves no drilling or cutting edge at all, so a carbide drill has no role.

Finishing the internal surfaces of soft plastics needs gentle, low-heat cutting; the special hardness and high-temperature strength of carbide give no advantage and would be overkill.

The application that matches carbide's strengths is fast cutting of hard, tough metals.

Hence, the answer is High-speed machining of tough materials.