Here are my 2 cents:
A) Good songs that somehow I consider to be boring due excessive length and/ or unnecessary parts.
The Parchment: Yeah, it could be trimmed a good 4 minutes. There are really interesting sections here, but Steve went a bit over the top for my taste. Not that it's the only example in the band's repertoire, but what makes the song become a bit of a drag is that, despite most sections are indeed cool, there's not a single "WOW!" part as far as I'm concerned. Nonetheless still a cool track.
Senjutsu: This one's way easier for me: just shave 2 minutes out of the whole thing, since other than that the track's really cool.
The Time Machine: Another one that's easy to spot the reason why I think it's kinda boring: the intro. It's a forced recycling of The Talisman and, IMO, the song would sound way better without it. Then I would also repeat the "Edge Of Darkness" harmony a couple times less too.
Isle Of Avalon: Ok, this one's blatant IMO. I love this song and its lengthy build up to the chorus. But I think it's unnecessary repeating the whole thing a second time. Other than that, top tier stuff.
Starblind: I really like this tune: a true maelstrom of catchy yet complex riffs. Yet, much thanks to its intricate nature, I think it could use some serious decrease on repetition in some parts (mostly the intro and mid part). Still a really cool song.
The Man who Would Be King: Another track that could use a tad bit trimming, since despite not considering it a bad composition, it's merely enjoyable. And "merely enjoyable" repeated too many times doesn't help.
Paschendale: First and foremost: amazing tune (perhaps the best one on this section)! Yet it's another case where it could be even better with a tad bit less repetition. Even so, it's already a great tune as it is, just think it's a bit tiring and I'm dead sure that some editing here and there would absolutely remove that feeling.
B ) Songs I consider to be boring because they're not my cup of tea.
Darkest Hour: Love the verses, yet IMO the chorus really deflates the whole tune. The operatic chorus really seems out of place IMO, and that combination is far from being enjoyable in my book. And not to mention that, seagulls included, there's no way this track should be more than 5 mins long. So much I always press the skip button every time this song is starting.
Empire Of The Clouds: I've already gave props to this monument more than once. It's indeed a really impressive work load. Yet, with really few exceptions, I think rock operas are really boring. And, despite really enjoying some sections (and risks taken like the inclusion of piano), the whole 18 minutes are too much for me, mainly due to its morphology.
C) Excessive repetition and redundant structures waters down some of my interest here:
Brave New World: Great intro, excellent crescendo and then I think everything else that comes after that is utterly dull and redundant. IMO the chorus is a snooze fest, the rest of the song is the same melody played uptempo and to make things even worst there's that mimicking guitar that really wreck my nerves. Starting with such brilliant melodies it's a waste, since I consider this track to be the epitome of boredom.
The Nomad: Excellent tune and excellent sections. Yet this is the perfect example of this type of tiring song: despite their brilliance, all sections are excessively repeated. Then, there's the bridge. A true masterpiece indeed, but it's blatant the laurels shouldn't be given primarily to Steve Harris to say the least.
D) Overplaying more than everything, since all songs here are truly great:
Fear Of The Dark: Despite sharing the opinion that this is a overrated tune, and the similarities to the Sisters Of Mercy on the opening riff, this is a really good track. That being said, you can't turn a rock without finding this thing playing underneath it.
Hallowed Be Thy Name: This track is not only good: it's arguably a masterpiece. Both the intro and harmonizer are simply stellar and I listen to them with roughly the same excitement I did 38 years ago. But when the verses kick in I somehow lose all interest. I can't really pinpointed when this happened first, yet I believe it's a fair amount of time now. And I really can't find a reason why this happens other than overplaying. On the other hand, when the solos kick in, the feeling of boredom ends and the song flows perfectly till the end. A strange case indeed.
Iron Maiden: Obvious reasons... exciting and uptempo punk metal yet played a million times (way more than any other Maiden song).
P.S. There are some tracks I didn't mentioned I think are boring as hell. But those I not only consider them to be boring... I think they're overall bad (like that "Don't you think I'm savior" thing).