Interestingly, this theory seems to be proven in Return of the Jedi by the Stormtrooper who shoots Leia off her speeder. To be clear, a big part of why everyone thinks Stormtroopers can't aim is ...

In The Empire Strikes Back, we see the first noticeably different stormtrooper variation on the ice planet of Hoth, when the rebel alliance is escaping evil Empire forces under the command of ...