This sounds like the air sealing in your unit isn't very good, as your unit shouldn't fall back to exterior temperature very quickly unless the insulation is in

This sounds like the air sealing in your unit isn't very good, as your unit shouldn't fall back to exterior temperature very quickly unless the insulation is insufficent or the air sealing is poor. Nevermind that insulation between you and othet units won't stop heat migration, just slows it down. FYI electric heat is common in older apartments and condos, but many of the newer buildings I've seen go up in Seattle are using natural gas.