Just as a Crescent Wrench, a Box End Wrench, and a Socket Wrench all will help you remove a nut from a bolt, each may have a little benefit over the other depending on the situation. So the same goes with Shooting Modes.
In the field I have encountered a fair amount wildlife photographers and/or birdographers. For some reason many of these fellow photographers have been convinced that Manual Mode is "the" mode.
I am going to share my humble opinion about shooting modes. Some may debate whether I am right or wrong, some may criticize my opinions, and even others may turn their nose at this post. That's okay.
I will have you know I am not seeking to offend anyone or imply I know all there is to know. I am simply sharing my thoughts in effort such thoughts may be helpful to someone.
Tv - Shutter Priority
Basically Tv is mode in which you select a desired shutter speed. The shutter speed you select will likely have an intended outcome. Since I photograph primarily wildlife and birds, I will focus my opinion of such subject matter.
If I am photographing mammals I may desire to have shutter speeds between 1/125 to 1/500th. Much really depends on the mammal, the activity, the action I am trying to capture, and so on.
If there is a bull Elk standing in a grassy field, do I really need a shutter speed of 1/1600th? In most cases, not in my book. Such high shutter speeds will force me to larger apertures and higher ISO's.
If I am photographing birds, lets say, perching birds, I may want shutter speeds between 1/500th and 1/1000th. Again, much depends on my desired results. With birds in flight I may want shutters from 1/800th to maybe as high as 1/2000th. Without trying to sound repetitive, desired results,, subject matters, and shooting conditions will impact my actual setting.
In Tv, I will select the shutter speed. I will let the camera determine the f/stop. I will use an ISO that helps achieve a desired range. What I mean is this...
If I would like a shutter speed of 1/100th and prefer f/stops to be f/8 or smaller, depending on the conditions and lighting I may choose a slightly higher ISO, lets say, ISO 640.
My point here is more about Tv. By setting my camera to Tv I am ensuring the shutter speeds I want.
Almost exclusively I use Tv for birds in flight shooting. My shutters speeds depend on the kinds of birds and desired stop-action.
With birds in flight there is not a lot of time for adjustments. Often one second the bird is in the sky, then at the tree line, then back in the sky. Tv Mode allows me to focus on other adjustments while not being concerned about my shutter speeds.
Av - Aperture Priority
Av is very similar to Tv except in this case you select the desired aperture or f/stop and let the camera select the shutter speed.
In many cases I may chose to use Av if the lighting is such that I am confident shutter speeds will not get too slow for the subject and scene I am shooting.
A good example when I use Av is when I am photographing small perching birds that may come within close range of me. From about 400mm on up we really need to be conscious of our f/stop settings, especially with focal lengths of 500mm, 600mm, or even higher.
You would be surprised just how short your depth of field (DOF) is at lest say, 20 feet. If you are not careful you could take a very well exposed image of a Dark Eye Junco and only to find out only the eye is in focus with the body and tail out of focus. That is what too short of DOF can do.
So Av, helps you control your desired DOF. If you set the aperture at f/8, the camera will select the shutter speed accordingly. Like Tv, Av allows me to focus on other adjustments while not being concerned about my f/stop or DOF.
To me Manual Mode is perfect when it comes to landscape, cityscape, portrait, and controlled environment photography.
In Manual Mode you will select both your shutter speed and f/stop according to your desired results. Getting this right takes a little time. Evaluating and metering light is often needed.
I find Manual Mode to be ideal when there many constants present with my scene, lighting, and subject, or I have the time to spend on all exposure settings.
If you are trying to capture birds in flight, would you set your camera to single shot and not use burst mode?
Or when taking birds in flight, would take your camera out of auto focus mode and insist on manual focus?
There are all kinds of tools within your camera designed to be used in the right scenario.
You are not less of a photographer if you use Tv or Av Modes.
Heck, there are times I use "P" Mode or Program Mode.
My intention is not to start a debate about the "right" shooting mode. My point is more so about busting any myths out there that have people convinced "pros" only use Manual Mode.
A professional mechanic is going to use all the tools they have in their tool box in order to get the best results.
A professional photographer would do the exact same thing.
Give these other modes a shot. I am wiling to bet you might get some better results and make taking photos a little more enjoyable.