The answer is PG-HQ and the hard work of its data entry guys has largely solved this problem.
Four years ago, before PG-HQ, and before the PG Expansions Explained geeklist on BGG, the only way to really know what a supplement required was to hold the scenario book in your hands. The AP website was and still is laughably,
deceptively vague about supplement needs.
Here is a comparison between the required games for Secret Weapons according to the back of the SW scenario book and the real required games list according to PG-HQ:
| Book-back Says | Actual Needs |
|---|
| Road to Berlin | Road to Berlin |
| Iron Curtain | Iron Curtain |
| Battle of the Bulge | Battle of the Bulge |
| Beyond Normandy | Beyond Normandy |
| Elsenborn Ridge | Elsenborn Ridge |
| Eastern Front |
| Guadalcanal |
| Sinister Forces |
| Afrika Korps |
| White Eagles |
| Edelweiss: Expanded |
| Airborne - IE |
| Desert Rats |
What do you call the behavior behind a disparity that large?
'Controversial' View on Supplements Using Multi-Sets
