Its important to know and thus be able to identify the sort of person you are dealing with, and thus know how to meet them, serve them. Some folks get along with everyone, others good with some and not with others.
Various typologies exist, such as Meyers-Briggs Psychological Indicator Test and Enneagram. The key is to consciously KNOW when to push or pull, when to wait and when to follow up.
Different types of persons also have different days of the week, times of day at which they function best, can be best reached, and you need to know who is best for in-person, phone, email, even Skype, or Facebook instant messaging.