We have used WL several times and always had success. For this Nov we WL at the 7 month mark for BCV or BLT and BCV came through the week before our 90 day mark!!! I was so shocked....so it is possible depending on when you got on the WL, size and where you want to be!!! Ours was a 2BR!!!!
A lot of it also depends on when you got on the waitlist. If you got on the waitlist early on, your chances are much better. If you just did it recently, not so much.
We have been successful 15% of the time and each time it's been when we called to check status. We have never had a wait list automatically get filled.
I've had 50% success. Success has always happened automatically (I get a letter or a call saying it came through) - not during a phone call to MS. Whenever I've called to check the waitlist, the CM never found a match during the call. Guess my experience is different than most.