Why would I use manual camera controls instead of the automatic modes?

I'm very new to digital photography, so I still haven't gotten the hang of all this exposure and ISO stuff, etc. I have a Canon EOS T3.

My question is how big of a difference does it make using manual settings rather than auto settings for everything? I've taken some pretty nice photos with all auto settings, and I'm not sure if it could have turned out any better using manual settings. I know that there are some people who have been in the game for years upon years, and to them they can notice the difference between photos taken with manual vs auto settings, but for my situation, do you think it really makes a difference? Is my camera smart enough to determine the best settings for me?

Also, lets say manual settings are better (which I'm sure they are, since they give you greater control). How often are you supposed to adjust your settings? Between every shot, considering they are unique shots? Or does it not matter about the object, but rather the lighting environment? So if I'm in a forest at 2:00 PM on a sunny bright day and I take photos for one hour, should I be constantly adjusting my settings between every unique shot to get the best out of it? Or do I usually just find one setting that works for the environment I'm in?

Answer

Applying manual controls allows one more freedom to enhance, manipulate and master applied photographic applications. By understanding the interaction of shutter speed, aperture, and ISO speed, photography — identified as "drawing with light" — can be utilized to its fullest potential.

Full creativity with the use of manual control can then be used to make those "How did they do that?" photos.