One the mighty Ken himself can reveal the true answer. A regular mortal pondering over such a question is more meaningless than Kim Kardashian's existence.
Yeah she's done, sadly. It all came down to a couple things but the biggest was a life changing event. She got a great job in northern FL and her husbands family also lived up there so they were relocating. Then she moved out of state a few years ago at least and she's got a different job now. The other issue was money. She felt she was being underpaid which definitely was not the case, IMO. $100 and soon $150 per scene was what she got, and she literally lived across the street from the beachside hotel I always stayed at in south FL (no travel/gas expense on her part). She was ready to move on....it happens! There are still a ton of scenes yet to be released and these were all filmed between July 2009 and October 2010. So yes, it has been 5 years since her last shoot. Quite a bit of footage to sort through, and all are excellent videos. They'll all eventually make their way into the lives and hearts of UMD'ers!