Lawyers often worry about their obligation to preserve relevant information.  As a result, one may direct their client to collect all potentially responsive information.  However, over-collecting is a significant cause of costly e-discovery.  So, what is a lawyer to do?

It is critical not to conflate preservation and collecting. 

While collecting is one way to preserve information, it is a very costly and inefficient preservation strategy.  Think of preservation as a means to ensure potentially relevant information is not deleted or discarded. This is a process driven exercise (i.e., suspend auto-deletion, cease recycling backup systems).   Collection, on the other hand, is a much more active exercise and should be thought of as the first link in a chain toward producing documents to your adversary.   In other words, collection involves “collecting” data from the universe of what has been preserved but it does not necessarily mean you will collect everything you preserved.   And, remember, not every document collected will be produced.  Rather, collected material must be processed, and then reviewed for responsiveness and privilege.