It depends on the source. Articles move up two ways. One is by votes, the other is by resubmission by different users. Peak times also mean peak competition.
If you are the first to post an article from a commonly frequented site such as TechCrunch, then it will tend to gain exposure because others are submitting it.
On the other hand, I've found that posting articles from less mainstream sources benefit from sitting longer on the "New" page. This means posting during times of lower activity. I have woken up to find something I posted just before bed has gained significant traction.
If you are the first to post an article from a commonly frequented site such as TechCrunch, then it will tend to gain exposure because others are submitting it.
On the other hand, I've found that posting articles from less mainstream sources benefit from sitting longer on the "New" page. This means posting during times of lower activity. I have woken up to find something I posted just before bed has gained significant traction.