On our recent visit, they were strictly enforcing the Fast Pass times.
To be fair, that seemed to be because a LOT of guests would try to simply bluff their way into the Fast Pass line whenever they felt like it (e.g. they'd go to the FP machines and then straight to the FP line even though their return time wasn't for hours). I think the cast members were turning people away every single time we got in line. It was quite chaotic and a little aggravating as the FP lines took a lot longer than usual because the cast members had to keep trying to turn away irate guests who seemed to think that they could use their Fast Passes whenever convenient for them.
On a related note, they didn't hand out Fast Passes when rides broke down which I found to be disappointing. And rides broke down quite a lot (twice when we were in line for ... Snow White or maybe it was Pinocchio, twice for Big Thunder Mountain, once for It's a Small World, etc).