I was at DL on Saturday and also had a 30 minute waiting period just as @RSoxNo1 said. Still worth it in my eyes as I was able to snag FPs for IJA, Star Tours, and BTM, all after 7 pm, something I never was able to do in the past. And this was on an exceptionally crowded day, as well.
I used maxpass over Labor Day weekend and had the same experience as Matt. As soon as you scan your pass at the ride entrance you could make another fast pass with no delay.
The 30 minutes delay only showed until the pass was redeemed.