On the really badly stuck ones, also disconnect the brake line and unbolt the wheel cylinder from the backing plate. Then the whole assembly, drum, shoes, wheel cylinder and all can be removed. The parking brake cable might be a little tricky, but it gives you room to work from inside the drum to free up rusty parts and/or apply penetrating oil.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!