A dungeon can't be a rule.
You clearly lack experience with certain publishers.
Gideon's
Justifiers RPG, all the adventures I've gotten have 1/5 new rules content, 1/5 sourcebook, 2/5 adventure, and the remaining 5th varies between which of those three.
Traveller,
Adventure 5: Trillian Credit Squadron is indeed Bk5-80 part 2, and includes errata for Bk5-80.
The Traveller Adventure has a subset of the Alien Module: Vargr, explicitly states things aboout the OTU and jump destinations.
Double Aventure Marooned/Marooned Alone has the operational rules for the ATV from the core rules vehicles list. Several of the adventures also canonically defined portions of the setting; The
Spinward Marches Campaign is a handful of pages of adventure, mostly sourcebook on the 5th Frontier War (a timeline advancement sourcebook), a reprint of the rules material from
Supplement 4: Citizens of the Imperium, and one of 5 slightly differing canonical maps and world listings of the Spinward Marches between IY 1100 and 1117. Marc, Loren, and Frank mixed rules supplement and adventure repeatedly, not just in Traveller, but also in 2300, Twilight 2000 1e and 2e (rivercraft rules?
Pirates of the Vistulq...etc)
West End included errata sheets in some adventures... not for the adventure, but for the
Star Wars Roleplaying Game and the
Star Wars Sourcebook...
A number of smaller games, the handfull or less of adventure or subsetting sourcebooks are also supplements. See also Pendragon editions 1-4 ... Each of the books was 2-3 adventures, a regional sourcebook, and several had expansion rules material (
North of the Wall, for example, added pictish character gen.)