Enjoy your trip. So glad to hear that you are having a wonderful time.
For the safari and zone restrictions: It is true that each zone is very large and that you can see a lot within one zone. However, if your target is to see the tigers, it might be a huge advantage if the ranger can choose zones freely because he might have seen tigers in a certain zone earlier same day or might hear rumours of where tigers can be seen at the moment, thus changing to a certain zone can be good.