Preparing Earthbox/fertilizer placement

[KC612]

Good morning All,
Is there a reason why I wouldn't be able to just mix organic fertilizer throughout the medium?  The instructions show to put it in one spot kind of away from the plants. 

[gardendoc]

The fertilizer is placed on top of the media to allow the nutrients to be released over time as the current of water moves up through the potting mix. This also allows for easier replenishment when transitioning between crops.