my point is, that without a "soft" ribcage, it is impossible to get yourself into the correct position for "good posture" because the ribs just won't go to the proper place. Also, the forward head goes along with this. It just gets stuck there until you can find someone who understands and can help you get it unstuck.

also, oft times if the lats or quadratus muscles are too tight, then either or both will work to push the ribcage up. In which case, no amount of working on the scalenes or shoulder muscles will get the rib cage to come down.

Hellerwork and/or myofascial release is extremely useful in these cases to loosen the muscles, THEN one can work to keep them loose on their own. They are almost impossible to really stretch out on your own, much like some of the upper shoulder/neck muscles.