I agree they are but ...
Halloween: same Shape costumes as previous years, couple reused Loomis costumes
SoX: there's three primary costume designs used repeatedly
HDD: one baby-faced killer mask repeated throughout
Tales: pigs from Scarcrow, lion from ST 3, HHN bear from 2015
TrT: half the costumes/sets from zone last year, plus the wolf from AWiL/standard woods set (still in my top two, but being realistic here)
DX: zombie masks repainted day-glo
Harvest zone: scarecrows
F&F zone: literally just coveralls
Poltergeist and Graveyard and Slaughter Sinema were the pimp houses this year, Klowns, Chucky and Traditions the pimp zones. An 11th and 12th house would have been thrown together from existing materials. The resources are't there to design a dozen top level houses.
This is a fair take that we don't talk about enough. There aren't enough materials to create ten (much less eleven or twelve) ultra deluxe mazes; inevitably, some are going to be carefully recycled or remixed. Hollywood's the same way --
Halloween: reusing a plethora of existing Halloween masks, props, costumes, and domestic sets (so many domestic sets)
Terror Tram: literally almost all recycled this year; Pig heads from SAW & AHS Roanoke, scarecrows from SZ1 last year, "Killbilly" overall generics, Hollywood Harry costumes/masks/props, generic clown masks/costumes/set pieces from the last decade
Trick r Treat/Stranger Things: literally the park's entire archive of forest materials (there's a reason there's no forest in Monsters)
Toxxic Tunnel: literal reuse of everything last year aside from a few new off-the-shelf masks
Holidayz in Hell: really smart redeployment of existing holiday decorations and other props (i.e. House of Horrors wolf finds a home here); money went into the new masks
Purge: many of the masks are new/specific to the film, but much of the set dressing, props, and scenic are pulled from generic urban/alley sets and earlier Purge zones
Blumhouse: no coincidence that Truth or Dare takes place almost entirely in an Abbey resembling La Llorona sets, Unfriended is in generic domestic sets, and The Girl straight up reuses Murder House hallways/walls
The "pimp" mazes for Hollywood are Stranger Things, Poltergeist, and, of course, Monsters. SZ1 got the most love in terms of new costumes/masks.