Why so long to get to sheriff's sale following BK discharge

[Ryan W.]

I am looking at a foreclosure that is approaching the sheriff's sale date.  The original foreclosure complaint was filed in 2007 and the judgment entered and initial writ issued in 2009.  The owners then filed for BK protection (Ch. 7) and received a discharge in 2012.  The bank has obtained two writs of execution since the BK ended and the property is now scheduled for a sheriff's sale next month.  I am wondering why it has taken so long since the end of the bankruptcy (4+ years) for this property to end up on the sheriff's sale list.  Is it just a matter of the bank's (lack of) diligence in enforcing its lien, or are there other post-bankruptcy issues/factors that result in the delay not apparent from the BK or foreclosure court dockets.  

I realize every situation is different and the exact reason for the delay may be unknowable, but I am curious to hear your thoughts on possible reasons that I should keep in mind as I pursue a potential deal on this property

Thanks in advance for your replies.