By wave 8 I could stand at my arrow restock area and shoot forever, killing the ants from across the entire screen before they even were visible.
When you buy things from the store you still shoot arrows.
If ants climb a tower and then the tower is destroyed they will fly across the screen in the air and won't be able to hurt you even if they get to the right side. (this was more amusing than anything)
It's a *lot* of clicking, and the waves are very long and slow.