With the onset of the foreclosure craze has come a barrage of information on the internet regarding how to delay an eviction. It used to be that very few were savvy enough to drag out an eviction for too long. If a tenant doesn't do anything and is fairly easy to serve, the Sheriff can come within 3-4 weeks from the date of the filing of the complaint.
However, most tenants and/or occupants are filing answers -- which means that the case must be set for trial and it is a good idea to be represented by an attorney for the court appearance -- or they are filing Demurrers (documents which say the complaint or the notice is wrong on its face) or Motions to Quash Service (process server goofed). In fact, I had a case recently where the tenant filed a motion to remove the case from state court to federal district court, and we had to hire an attorney with federal court experience and licensing to file objections and get it remanded back down to state court.
Evictions are becoming increasingly more difficult to do because of all the techniques floating around on the internet. A property owner cannot count on the 4-6 week rule for possession any more. The length of time all depends on the knowledge of legal procedures by the tenant and many of them have gotten quite brazen with the lengths that they will go through to manipulate the legal system.