Training local troops is one of the primary missions of Special Forces. Originally, SF was founded to wage guerilla and counter guerilla warfare in places like Vietnam. A SF "A Team" (typically about 12 men) is set up to go into a local area and link up with the people living there (that explains their language skills). They then recruit, train, equip, and lead into battle up to a battalion of the locals. They can also perform the direct action missions like the SEALS and Rangers.

The Afghani troops often have years of combat experience and are very brave. However, most of them aren't very disciplined. Their bravery often causes them to do things that just aren't smart, like exposing themselves on a ridgeline or sticking up their heads at inopportune moments. Not only can that kind of thing get individual soldiers killed, it can give away the position of entire units. They also need to learn how to work efficiently in both small unit action and coordinated action with other units. One goal would be for then to think of themselves as Afghanis instead of belonging to a particular ethnic group. There just isn't any cohesion between different groups. They also need to learn how to use modern weapons effectively. Bravery alone isn't enough.

Marching has one real purpose to a soldier and that's training to obey orders quickly without question. That's really just the first step to establishing discipline in small units.