AA, Aalska, Virgin, and the Avios programs went to unlimited redemptions last last year, at least for USA-based accounts. I’ve redeemed both AA and Alaska twice in the same month. I was going to say that Hilton and Flying Blue were the ‘once per 30/60 days’ holdouts but I just went back and looked and the time limits seem to be gone from there now too- it was there when I did my most recent FB redemption a few weeks back.

I totally depleted my Hilton balance last year for Jackson Hole so it would be awesome to be able to rebuild that account a bit via surveys.