Therein lies the difficulty for people - knowing when this review/parsing process happens.

From Ms Jimbo's battles with HQ (12 years as gold.. we're experienced), this review is done by flight and with increasing frequency as the date approaches. During this process inventory is moved between buckets, possibly creating award/upgrade availability at the same time as availability in cheaper fares. This availability is then filled by waitlist priority. She got the impression that waitlists were not specifically reviewed outside of the usual flight-centric reviews, except of course for diamonds or anyone else with similar priority (not golds in my experience) - probably what you referred to as the "active" waitlists.

The only evidence I have of this in practice is noting that as a gold awaiting award availability, the same day I got confirmed in PL, Z also became available for purchase and other buckets moved around. Generally the comments and behaviour I've received from HQ have been the same, whether waitlisted for free flights/upgrades or in L Elite (which Saigon always used to book into for London) - ie need to wait for a review of the flight and if a few months out, it would be a while.

Exceptionally it possible to push them to review the inventory for a flight earlier, thus releasing a seat into the bucket you require. It is also possible to get a higher priority than you are entitled to. From what you say above, this probably means getting a PA despite being gold. Again highly exceptional. The first "exceptional" process happened to me after endless pushing on an L Elite reservation by Ms Jimbo. She managed to embarrass them somehow and they were on the defensive. They considered upgrading me to Diamond to achieve the higher priority that way (!) - but then instead said that inventory control would be instructed to review the flight. She was onto someone quite senior. A few hours later not only did I get my L Elite seat, but L availability appeared online too, so it wasn't a one off seat that was made available. An example of the second exceptional process was when my mother was ill and at short noticed I managed to get a day return SGN-TPE-LHR (!) in L Elite. L out was available, but back was confirmed a few hours later.

By the way, I phoned TPE at about 11am yesterday for a V Elite upgrade to PL next week. It got confirmed at 5.30pm. Perhaps this terrible wait of over 6 hours is the "diamond lite" service (aka PA- )..