Firstly understanding what you want to manage is key I.e understanding the environment.After this collect data about the environment ,then one has to safe cost and time by optimizing the sales route I.e knowing where and when to go to meet the target markets.Delegating duties is also a vital part in been able to manage a large territory as no one can do it all alone.Taking note of happenings on a day to day is important in managing a large territory as this enables you to mentor progress and know what to work on per time