I kinda agree too, I expect email traffic to be slower (though hopefully not non-existent) over the weekend and holidays etc. For example, you wouldn't expect an email from your supervisor on Christmas Day, unless you were really unlucky!

That doesn't mean you should have no support outside of office hours, but I think you have to be realistic. Of course, academics and students should be flexible when it comes to a big deadline such as paper writing etc.

Been away from e-mail for a few days so just read the latest on this post. I don't expect people to be available 24 hours but if people e-mail me in the evening and weekends then I assume they won't mind if I do the same to them.
Yes, I agree missing deadlines is bad time management but life gets in the way of work sometimes. I missed out two full days of working because my husband, who I am breaking up with, had a car accident, then a relative of his died and he was in a bad way, and even though we are separating I needed to be with him while he was going through a bad time. I'm sure everybody else has times when personal issues mean PhD work is delayed or not done as well as wanted. Luckily I am close enough to my supervisors to be able to tell them things like this and they are always very sympathetic.