From my understanding, its works great right after a tillage pass an you get the first good flush of seedlings. These dont have the root reserves to come back. Alot of market gardens us them across beds. Have seen the field mounted version for corn rows. Still leaves the weeds closer to the stalks.
Would think it would be time consuming for single row even on something as small as 2A. But, would think if a guy had a bad case of marestail on his hand. That it would be very effective an probably worth the investment for spot/patch issues.