In an interview with Dengeki Online, Kojima discussed the difficulties of creating a large open world, and their approach to the AI buddy system.
An important of the MGSV TGS presentations was dedicated to the buddy system, an option in the game that allows you to take helpers with you on missions. During the development of MGS2, the team had a hard time getting the AI companion (in this case, it was Solid Snake assisting Raiden) to work properly. For MGSV, Kojima Productions opted for a different kind of AI buddy. Instead of a more traditional companion, that is to say, one that follows you around and is at your side at all times, Quiet can look after herself. With her sniper she can provide back-up from a distance, or she can go on ahead and scout the area.
Kojima also talked about the difficulties of creating a vast open world. He placed landmarks throughout the environment to make sure players won’t be completely lost without the iDroid. Still, taking the recently shown African jungle as an example, Kojima said that without this device players are likely to lose their way, given the sheer size of the location.
Source: Dengeki Online, MGS.be