Wraiths can definitely be assholes and not become Spectres. There are Wraiths who melt fellow Wraiths into coins and ashtrays every single day, have been doing so for a long time, and aren't Spectres.

A Wraith might want to rule a Necropolis with an iron fist and make a public example of every renegade regardless of innocence or severity of crime and their Shadow might be The Abuser, making them want to inflict pain on others the same way they were once.

Another important thing to consider, it's only in extreme cases where Shadows are pushing the Psyche as hard as possible, they usually want the fall to be slow and agonizing. It might take 20 years, it might take 20 minutes, who knows?