From what I heard before, background complete means both security and criminality are complete.Where all the files getting background done in first couple weeks, I am trying to understand if this indicate making the case non-routine????
Some people get it cleared instantly but because they batch request they might be completed in couple of days.
Some others might be waiting for security to clear out.
Usually few weeks to months.
There are cases where non-routine for physical presence, missing entries for example or suspecting residency fraud, or pending investigations.
But these are rare, usually non-routine is quality assurance or security.