Three Types of Professional Contacts
Your professional contacts consist of far more than friends and allies. They also include information resources, perspective providers, and adversaries.
Take the last group first. An adversary one week may be an ally the next. The nature of the relationship may even shift from hour to hour and many adversaries would never admit to the role. It makes sense, as the saying goes, to keep your friends close and your enemies closer, in order to learn what they are up to. Some people don't realize the extent of their opposition or how their tactics are perceived. Those deserve special attention lest they do you a "favor" that is anything but.
The information resources may be acquaintances or friends but their main professional role is to let you know what's going on in their area. They resemble the informers in the old detective movies who, over a cup of coffee, can give a mainly unexpurgated version of the local developments. Depending upon your job, the information resources can be formally recognized as liaisons, which can make them double-agents. You should not worry about that just so you get the information you're after.
The perspective providers need not be in your organization or profession. Their role is to give wise advice as bluntly as possible and to warn when you are about to make a foolish or dangerous move. Out of the three types, the perspective providers are the most valuable.
They are also the least-used.