Yeah, that is what I usually do. But you have to realize.. I don't do graphic heavy websites. If you see the sites I do, its mostly programming. So this may not be the method you prefer.

Another good way is to crop your .png file and saving that as another name. That works well too. I usually don't do that because I accidentally saved my original once and lost everything, thats why I stick with the create new blank document, copy, past, and save.