Careful reading Halo 5 comments.

[Insidb]

Tachikoma said:

So responding to accusations of me lying about how long it took to complete warrants being told to "grow up"? right. 
I was dissappointed on the length because I completed it in that amount of time just playing it casually, the same as most people would, I wasn't skipping cutscenes, I wasn't sprinting through levels, just playing it normally.

After all of the articles stating the campaign was 15hr+ i feel quite well within my rights to be dissapointed by less than 7 hours, even if set to normal, i'll likely play it again on heroic when looking for the remaining 3 skulls i didn't find playing through the first time at some point in the future.

Also, i'm pretty sure the majority of people that will be playing Halo 5 will, just like me, play through it on normal too.

This is pure validation of my previous "deja vu" comment about The Order: 1886 and the perils of fanboyism. The length narrrative reared its ugly head, many days prior to release. In both instances, the opposite fan base harped on the value of length and (without warrant) dismissed the accounts of those who had already completed the game. We should just call this repeated nonsense, "The Order Effect." For those ripping you apart, karma is still a b*tch.