You may be right about some albums of some bands/musicians, but I don't think that is the case with Maiden. A "clear and obvious winner" does not mean a bad album. Just remember, Phantom, Hallowed, even Infinite Dreams did not get much competition either. Actually the only time we had a real competition was with the NPFTD album, one of the lowest ranked in IM discography. Another example is Queen's "A Night At The Opera" which is an excellent album, but I'm sure Bohemian Rhapsody would be the obvious winner in a poll.
In summary it may also mean that an album full of great songs with one standing-out masterpiece.
Yes, there are multiple possibilities.
But when I compare X factor to No Prayer for example. No prayer seems to have a very good spread, ther are maybe two or three songs that are noones fav, but lots of other candidates for favs, to me it shows that there is some consistent quality going on in that album. Despite the popular notion that that is a bad album, I think it is actually a good album.
X factor has many songs that noone would ever consider good enough to be the best. Personally i don't think Sign of the cross is a particularly spectacular song. It's just long and has a very, very quiet part at the beginning and in the middle.
I personally think if you put X factor songs into other albums, like Powerslave, TNOTB, Piece of mind, SIT they would typically be deemed the worst it those albums. Whereas with an album like Powerslave, although most people gravitate towards Rime and Powerslave, I think pretty much any song from that album placed in other albums would easily be near the best in those albums. So Powerslave is of the type where there kindof is a clear two top songs, but the album is very strong. Fear of the Dark is of the kind where there is a clear best but overall the rest of the songs are very weak.
With regards to Seventh Son, I think it is very telling that Infinite dreams is head and shoulders above the rest of the songs on that album. I know popular opinion is that this is an overall great album made in the golden period of Maiden's history, with the classic lineup and the best producer. But I think most of the songs are not standout songs. If you put them in other albums they would not stand out as great memorable songs. I think SSoaSS is highly overrated.
Anyway, I'm no authority on the matter, I just have my own opinions.