A friend of mine who is a defense lawyer told me that in 50 % of the cases he defends he is not served written discovery.
I can imagine that there might be a tactical reason not to serve written discovery in a particular case. I can also say that that situation has not arise in my 24 years of practice.
I have found it best to almost always serve written discovery with the complaint. In many cases, we also serve a notice to depose the individual defendant or a corporate representative at a date we estimate to be 60 days after service of the complaint, when we will have an answer and the discovery in hand. We will almost always modify the date to accomodate the defendant and the defendant’s lawyer, but we like to get the case moving right off the bat.
Clients want cases over. Serving written discovery early helps accomplish that goal.