Warren in Lancaster, PA
I ended up doing 800 feet with my iron (and still working) before I sharpened it. It took extra time to sharpen the iron, much duller than it has ever been since I acquired it.

As a professional, it is much more economical to sharpen several times in this amount of work rather than to put it off for so long. Sharpening is much faster when it is done often, but more importantly the tool works much better, so it is faster to true up an edge. And you don't have to worry about starting off Monday morning with a sore elbow or shoulder or something.