VA delays in general are the result of an understaffed agency in proportion to the number of new claims being filed.  The backlog of claims is now reported at over 1,000,000 claims to be decided.  The report of the Chairman of the Board of Veterans' Appeals lends some insight into how long a typical case takes to be decided.  

The BVA Chairman reports that it takes an average of 257 days for the Regional Office to decide an appeal after a Notice of Disagreement is received.  After a Veteran files a VA Form 9 Appeal to the Board, it takes the Regional Office 585 days merely to certify the appeal to the Board.  After the appeal is certified, it takes 240 days for the BVA to issue a decision.  Thus, the appeal of the typical case takes 1082 days for the Board to issue a decision.  

And, if the BVA remands the case back to the Board for additional processing, it takes an average of 427 days for the claim to be returned to the Board.