Gotta set your alarm to get those R savers!
You should have seen the panic in my face when I was having dinner with my +1 last year, and realised that it had been about 8 hours since inventory would have been released for our preferred departure date. Luckily, they were available.
But, when only waitlist was available, I've called before and asked for the waitlist to be cleared, knowing we were the only two on it, and there were still 10 empty suites. They asked if there was any special occasion or reason for wanting to clear the waitlist, said they would email the (insert job title here, inventory controller?) and I would hear back in 2-3 days. I received an email on my booking confirmation not 30 minutes later. Same with blocked seats (row 11 on a350), I called and asked for them to be un-blocked. Again, they had to email a seat inventory manager, and about an hour later had a "your seat change has been confirmed" email.