Like Eric said, don't mist or soak a snake in blue because it will screw up the liquid between the skins. You can raise humidity after they come out of blue but I have run 50-60% humidity all the time with no moist hides and my snakes all shed in 1 piece like a rolled up sock. Also some snakes just take longer to shed. Both of my BCIs take about 2 weeks to shed where as my BP only takes about a week. I wouldn't worry about, they will shed when they shed. Just keep a constant 50%+ humidity and you will be golden. Also some snakes will look wrinkly especially around the head/neck area just before they shed(like a day or 2) so that can be a good indicator too.
Oh also one other thing, once your snake sheds, check that both eye caps came off and the end of the tail is shed free. Those a 2 important things to make sure after a shed.