I am a little surprised at how many people say it is absolutely BU to ever leave a screaming child for 5 minutes.
Yet if the OP comes on here tomorrow to say 'I am totally stressed out, I feel I can't cope any more, dd screams all the time, I feel like murdering her'- then what are we all going to answer her?
Yes, that's right, we will. 'There dear, not to worry, just put her down in her cot and go into another room, make yourself a cup of tea, take deep breaths, she won't come to any harm'.
So why not take those 5 minutes before you get to the murderous state? We are not talking about a neglected child sobbing in her cot for hours- just a short break to shovel food into your mouth and get that blood pressure down a bit.
I did not often leave my children to scream, that must be admitted. But there were occasions when I needed to leave one of them for a short while, to deal with the other. And there were times when they were tantrumming and I simply walked out of the room(acceptable Mumsnet practice, non?).
If I had wanted to establish proper sleep routines (and not been the lazy slob I was ) then I'm sure that would have involved letting dd scream herself to sleep on occasion. She was that kind of child. Not all mums who do sleep routines are cruel and abusive.
And as someone mentioned, some children actually wind themselves up more if you fuss around them- walking away can help. Particularly if it makes you less tense, as children pick up on that.
I liked Alicet's sensible and balanced post.