You have to watch your metering too. When you are using shutter priority, it will usually adjust the aperture accordingly. Using spot metering will give you metering based on the center area, where you are focusing. The reason I let the camera do the aperture based on shutter speed is for conditions where there are dark and light skies, with varying degrees on each pass. Chino this year was a great example of challenging conditions. Not all of them will work (true even on sunny bright days), but that's been what works for me. The one thing you may also have to contend with in that situation is when the shutter speed isn't slow enough to let the light in. Then you have two choices; 1. Get out of your comfort zone and go slower on the shutter speed, or 2. Up the ISO setting and deal with some grain. Both have benefits and drawbacks. BUT, getting out of your comfort zone can bring you shots that you may never have even attempted before. My Mustang pan shot at Riverside a few years ago was WAY out of my comfort zone. The result was a shot that has been a good seller and the most views on airplane pictures. I did that one on a dare, and it worked.
So practice shooting out of your comfort zone at other times, and when you need it, the knowledge will pay off big time. Kamikaze Kamera taught me how to take shots where I couldn't put my head (like leaning into a cockpit to get a photo of the cockpit, or shooting directly behind me).