No, not saying that, don't think they'd do that. You're right, if you book it at 3:30, you could still go in at 4 and use the FP till 4:30, so you'd have a half hour to use it. Just don't, say, use your MB, and go in between 3:30 and 4, thinking it's okay since you have a FP, cause it would use a days' ticket before 4 p.m.