Do you not sharpen them in between? I've had to spend hours sorting out knives that have been left far too long without sharpening, but my routine is to spend about 15 minutes sharpening them every weekend. Then they're always sharp and never get into a terrible state and need remedial work.
My knives get noticeably suboptimal in a couple of weeks without sharpening, so if I left it 6 months they'd be blunt pretty much all the time.