He only had 3 minutes between the time of the voice like sounds and thud caught on the neighbor's security camera and when his car peeled out, leaving. And if you go by the theory proposed to Dateline, he attacked Xana, then stabbed/sliced Ethan while hitting an artery, and then "carved" his legs. Then he would have had to run out, get enough bloody attire off him that he could safely get in his car (and we don't know for sure if he was parked right out front, or up the hill behind), and drive off.
So, IMHO, the sitting would have been very very brief. And likely of a practical purpose (catch breath) instead of for voyeuristic intent.