I live in Germany. 'Ja' here means 'ich stimme zu' only when explicitly asked. That's why Germans stick 'Ja?' after every second sentence. Ja? In general, 'ja-a...' means 'I hear you', same as almost everywhere else. That has been my experience.
>>nuance+hP
And why do they say ‘right?’ every time? Because without it my ‘ja’ does not mean ‘yes, sir’, but rather ‘I hear you, go on’. So, same as everywhere else.