I've always thought USA 6-7 were not true Schomburg covers...at least Caps body and face don't match up to what I say is is typical schomburg Cap ( USA 8,10, Cap 28 etc). This was discussed in a thread many moons ago, but schomburg was drawing so many covers at the time perhaps he did the background layouts on the 7 (the planes look schomburg --look at USA 8 and All Selects 1-2) but not the Cap/Bucky figures. The 6-7 are signed Schomburg but it looks more like a Syd Shores cover to me (check Caps 20-25,30,32). Even the inside of Caps shield on USA 7 doesn't look Schomburg like (All Select 1).
That said, Schomburg was the best WWII cover artist. Suspense 3 might be in top 5 Schomburg covers but my favorites have always been All Selects 1-2, USA 8/10, and Cap 33.