This is correct. Symbian is divided into branches.
If problem was found in one branch release it was that persons responsibility to notify other related branches. This caused finger pointing when trying to issue fix sometimes because if the person noticing a problem was seen as "below" the other engineers, they did not carry the same influence in their reports. The problem was maybe only they see it because they did something wrong. They were seen being below other engineer teams in skill level. It was not uncommon for verbal insults to be thrown due to egos.
Meanwhile problem turns into valid bug and gets released...