Why is it important to keep the leads and pile plumb (vertical) during driving of a vertical pile?

1. Plumb alignment is only an aesthetic preference
2. Out-of-plumb driving applies eccentric/bending loads that can damage the pile, cause it to wander off line, and stress the rig
3. Plumb leads increase the fuel efficiency of the hammer
4. Plumb alignment is unnecessary because the soil corrects the pile