Some recipes call for sifted flour before you measure and others don't call for any sifting. For those recipes I measure out the required amount, then I sift all my dry ingredients. Specially if I am making a cake.
This idea that you can aerate your dry ingredients with a whisk just doesn't fly with me. I find that by using a sifter, cakes are so much lighter. I have your grandmother's sifter. You crank the handle. Holding it up just high enough, but not to high that it will be all over the kitchen, makes a nice light fluffy pile. Then I spoon it into the wet ingredients a little at a time. I also sift it onto a large piece of wax paper. That little bit at the end, just pick it up and slide the rest into the bowl.
If I am making chicken fried steak or flouring pork chops, I still sift. Sometimes the old way is still the better way.