How about the whole "getting the Duke's help" issue? That was accomplished inside 108 seconds? You haven't answered anyone who brought up the point that the time it'd realistically take anyone to coordinate, talk, convince, direct, etc. in a situation like this would have been more than enough for the PCs to put on their armor.
Time to fly to the ducal palace while hasted: 2 rounds (it was 120 yards away)
Time to get past the guards to to see the duke: 2 rounds (the character had already been given the duke's blessing to come to see him whenever he wished)
Time to get to the duke's chamber: 1 round
Time to say "The vampires are attacking the now and killing the city guard. Can you help us?": 1 round (I just timed myself saying these words -- it took 4 seconds)
Time for the duke to cast Haste and Fly: 1 round
Time to fly back to the combat from inside the palace: 3 rounds
Given that the city had just held a public meeting called by the duke, a mere 5 hours before about the vampire threat and stationed an extra 80 troops on the earthwork walls around the tower because of what they perceived to be an impending disaster, it was not difficult to explain to the duke either that this event was happening nor the urgency of responding to said event.
While it would have taken 8 rounds to fly to the characters' house and back, the ducal palace, a mere 120 yards away took a total of 12-14 (you'll note that my timeline is only 10 rounds long as I no longer specifically remember what took how long) rounds to reach and summon help from (I'm not sure how the other two rounds were spent -- I think they probably involved further discussion between the sorceror and the duke).
In the whole chaos that was going on vampires are casting spells and herding people. How long does it take to herd 100 guards? I'd say another 10 minutes to herd. Is that an unreasonable time? That is where our opinions differ and it is just a matter of opinion. But what you are doing is assuming that you can get 100 people into a tower that has only 1-2 entrances at a rate of 25-30 a round. That is highly improbable even with dominated thralls.
Well, only 70 people were herded into the building. Also, remember that most of the mind-controlled people were not Dominated but rather, the victim of Mass Suggestion. Based on the width of the building's two doorways (20' each), I calculated that 12 people can pass into the building per second. You assert that this would take 10 minutes; I recommend that you look at fire drill times for elementary school students (less than two minutes in many cases) -- then compare the discipline of a group of trained, professional soldiers, highly accustomed to marching in formation, all of whom are 60' or less from the door through which they are required to march.