Usual advice is that you need to straighten your blade every week or two and then you can sharpen it every 6 months or even a year (depends on usage of course). To straighten the blade you use honing rod which many people mistake for sharpener.
I have a steel honing rod but it's never seemed to have much effect. Perhaps my technique isn't right.
I also have a ceramic sharpening rod, which I use to sharpen my breadknife. That's very effective, but different as it actually removes steel. I give my straight-edged knives a few strokes on each side on a 3000 grit whetstone every weekend, which seems to keep them nicely sharp. That will slowly wear them down but it hasn't done so noticeably yet so I expect the knives to last many years.
