Why might a court case be postponed for 6 months?

There are a lot of possible reasons. One would be if the accused wasn't medically or mentally fit for trial. Another would be if the accused had fled the jurisdiction and it was taking a long time to extradite him. If it's a very complex or serious case, it could also be that the accused's lawyer died or was otherwise unable to continue the case and a new lawyer needs time to familiarize himself with the case.