What is the biggest reason we delete images?

What would be the biggest reason we delete images, "out of focus images".
First thing we need to understand is that, the only subject that can be sharp in an image is that that the lens is focus on. That is physics, not me making stuff up. Closing your aperture down to F22 will NOT make the whole image sharp. Generally to get the best even detail in an image, you should shoot at between F8- F11. When you have this aperture it allows the light to hit the sensor, without too much distortion.
In the days of film when we shoot at F22 everything appeared to be sharp, this was due to the resolution that film could give you, and this was generally with very good paper and was around 75DPI. We now have resolution available to us in excess of 300DPI so we see the BLUR ramp. The BLUR ramp is when you see from in focus to out of focus. When we get to the nuts and bolts of an image, the image is more about out of focus than in focus. If you want the whole scene to be in focus you have to take more than one image then stack them together. There are a number of different programs for achieving this effect, more and more macro photography is being focal stacked and if you look at the landscape work of the likes of  Peter Eastway, you will see focal stacking at its best.

I believe that by using Back Button Focusing, will give you more in focus images than out of focus images. If you do not know what I am talking about look it up, practice and you will see results. it does take practice but I feel it is well worth it.