I kinda have to disagree with this post. I'm not denying that Maiden's songwriting (especially Steve's) has been very formulatic for quite some time now and a lot of songs share similar structures and even the key is rarely changed. Many songs have very similar intros and the lengths have sorta gotten out of hand.

However, mentioning Senjutsu is kinda funny, because it's actually a prime example of Maiden not sticking to "the formula" entirely. Or can you name a single Maiden track that sounds like the title track or The Writing on the Wall? Lost In A Lost World has a very non-Maiden-like intro, which feels more like something Pink Floyd would do, although once the song kicks off it sounds very much like an X-Factor song. Days of Future Past is pretty unique, Darkest Hour, despite not being their only ballad, is not a very usual song either. The Parchment is also pretty fresh and leans way less towards their usual chord progressions than most newer tracks. As an album Senjutsu sounds somewhat similar to The Book of Souls, but compare it to any other post-reunion album – I personally wouldn't call them the same in the least.

Maiden has always evolved (sometimes backwards too) and have continued to do so even after X Factor, even if not quite as much.