Originally Posted by 757DUD

Generally yes, however there is one exception. Berlin is connect to nearly every place in Germany by bus. However, this is a exception because of berlins history prior to 1989. (But you can still book it ;-))
https://www.berlinlinienbus.de/index.php


While I agree with ToGo, sometimes the plane is cheaper. It is always worth checking (esp. routes like ber-fra)
I definitly would recommend, that you first decide which places you want to see. And after you have decided which places you want to see, you can still find the cheapest way to get around.