Who, besides you maybe, would be looking at your photos zoomed in at more than full size.
Few electronic displays show a photo at full size. My display is 1600 x 1200 pixels. A full size 12 MP Nikon APS-C image is 4,288 × 2,848 pxels, which is way larger than my display.
normally for "full size" you mean the opposite of what you are thinking. At full size (i.e., 100%) you see blur or noise at their maximum; if image looks soft at full size, indeed it is. If you want a perfectly focused picture, the point you focused on should be crisp at 100% (depending also on lens quality, aperture, etc). Resized like in the camera screen or at monitor, some defect could be invisible. Printing is another matter.
For example....I just took a portrait of a girl that I really like but it is pretty blurry at full resolution.
So I sharpened the heck out of her eyes, added a very sharp catchlight in her eye. Then I resized it to 800 for internet use and it looks sharp, no one would ever know it was actually a pretty blurry shot.
Sharpness is overrated...especially when shooting people.