The underground tunnels of Shibuya Station in Tokyo are well known for being a complex mess. There are so many entrances going into the stations of Tokyo Metro and Tokyu Electric Railway. This will change by November 1st, where Tokyu and Tokyo Metro will change all the exit numbers of their stations.
The most significant change is to assign zones to the exit numbers, from A to C, instead of just numbers. The assignment is geographically based, using the JR Shibuya Station as the demarcation line. All exits on the west of JR Shibuya Station are in the A zone. And all exits on the east will be in zones B. Exits in zone C are mostly the exits to the south of JR Shibuya Station.
Hopefully, this change will make navigation in Shibuya a bit easier. Bear in mind though, that these changes are only for Tokyo Metro and Tokyu Electric exits. For JR Shibuya Station, it is still going to be either East & Miyamasu-zaka exits on the east, and West & Hachiko exits on the west.