Alright so I'm sharing these screenshots of me queueing for Ridorana. You can see both the time elapsed and my irl time.
and yeah it took 40 minutes for it to pop
But to be fair about this, the reason I was doing this was for my Shb relic; where I need to farm 18 vexatious memories. So while I was waiting for the queue, I did FATEs in the SB zones to gather additional memories so my time wasnt wasted.
My point still stands though, you can still queue up for these old raids and your time will vary but its still possible, since they're within the alliance roulette pool. Which I imagine the algorithm will usually tip into whatever favor players wind up queueing for at the time.