When I had the older-style Navigation, (where it reads from a DVD as opposed to the HDD) there were about three updates per year, but that was just GB & Ireland. It seems now that all of Europe is in one big set that it is only updated annually. Why those roads missed the cut is anyones guess - a new (minor) road opened near me around October which wasn't on the 2011 set that came with the car but did appear after I upgraded to 2012 maps.
Current: 2013 F10 520d M-Sport, Professional Media, Visibility Pack, Reversing Camera, DAB
Previous: 2011 F10 520d M-Sport, 2008 320i M-Sport Coupe, 2002 325i, 2001 318i valvetronic, 1998 318i, 1996 525i, 1990 Porsche 944S2