Hello all, brand new to the site! (be nice to the newb) Thought I might help out a bit since I've been attending HHN for well over 18 years and also went this past Saturday, Sept 28th with a party of 7.
My only "cheat", I'm an Annual Passholder and took advantage of the early entry for 3 houses (Walking Dead, Llorona & AfterLife) between 5-6:30...it saved a TON of time (as it has for the last 3+ years they've been doing this). By 6:30, I walked right into Havoc and had to wait anywhere between 10-30 mins for the 4 houses in front of the park (no surprise there), managed to do the 10pm B&T show and skipped Rocky Horror (saw it last time it was at HHN) & redid La Llorona instead, which only had a 15 minute wait later on...did the new Twirl & Hurl (hadn't done this during the day since they opened it) left the park at about 11:30pm...all this with NO EXPRESS PASS!
From what I observed,Cabin In the Woods, AWIL, Evil Dead & Walking Dead remained at or ABOVE 45 minutes throughout the whole night! The other 4 went as high as 30-35 minutes, but as the evening wore on, as low as 10 minutes. Keep in mind this is September, I'd guess these numbers might be about the same this upcoming weekend, and to a lesser extent, the weekend of Oct 10-13.
If you are not an AP and were there on a night they close at midnight (straight 5 1/2 hours), from prior experience, I say you can LIKELY do all the houses IF you get to the gate at, say, no later then 5:45 (they almost always open the gates early) and hit the houses in counter-clockwise order and try to do it NON STOP (0-1 restroom break, 0 food/drink breaks), you should be able to do 'em all. Doing both shows might be a little tougher, especially the deeper you get in October. Good luck OP!
BTW, had a BLAST!!!!
Favorite houses: AWIL, La Llorona (I'm latin, so maybe partial to the legend...freaked out my daughter both times we did it..mission accomplished)
Least favs: Resident Evil, Havoc 2 (the military theme just isn't my "thing" for haunted houses, awesome sets & actors though)