I have never stacked focus. Have you? Do you know what focus stacking is? It’s the technique in which you take multiple exposures, with multiple points of focus, and combine them together in the computer (into a "stack") and choose only the sharpest bits from each shot to create an overall sharper image with greater depth of field than what would have been possible with the single in-camera image alone. This is most useful, as you might imagine, with very shallow depth of field. And that makes it the most obvious fix for macro photos in which not quite every bit of your tiny subject is tack sharp. You can fix that with focus stacking. Mike Panic writes about the technique on the Light Stalking blog, and he demonstrates how you too can get sharp macro images of an entire subject, rather than settling for just one part being perfectly in focus. The article includes a great example too, as manifested on a bug’s millions of eyes photographed by Thomas Shahan.