Each thread in a computer runs under a specific user account. Shared folder have security settings, i.e. they are subject to ACL-based access control, so that some users may have access permission and others may not. This means that the thread in your program may be able to "see" some shared folders, while other threads in the same computer (including the interactive user using the desktop) might be unable to "see" those folders.
In summary: you should assume very little.Lepide