As you know, Lync have its own address book (AB) that downloaded by clients. By default, the download and update process of address boook in Lync 2010/2013 triggered in first 60 minutes (random time) after program start. In our company this situation was considered as wrong, thus I had to find solution how to ensure guaranteed updating of Lync address book right after the client starts. Also, there are other issues with delta-updating of address book, like a big delays (5-10 days) after changes in Active Directory are repliacted to Lync AB. 

The consequences of such behavior: