Just some recent experience. I was on the waitlist for CX 469 on February 12, for Y+, J and F. Checked every day for the past week or so to see if any of those would clear, and at the same time would re-check award booking availabilities. Lo and behold this morning checked and saw there was an opening Y+ seat for the flight, but nothing had cleared for my waitlist. CX's waitlist is clearly ineffective.