Given her history, would you leave your kids alone with her?
Now that is a very difficult question to answer.
Would I have left her?
Obviously from hindsight and all the claims being made by the shrinks one would tend to want to say NO, DEFINITELY NOT.
Based on what Mr. Yates knew at the time and what he may have been told or not told... I would say I probably would.
Obviously Mr. Yates was trying not to leave her at home. He new she was currently fragile and not herself - we know this because the mother-in-law was on her way and was running late. All prior evidence was that she was a danger to herself and not others. She had been recently released by the last Dr. and was supposedly recovering from her recent depression. She had was highly intelligent and an avid mother... She seemed 'okay' when he left - so probably so.
I personally I doubt the Dr. warnings were anywhere near as strigent or clear cut as they are currently trying to make them seem. Some of these communications were probably only made to Mrs. Yates and not to Mr. Yates.
She planned this crime. She waited hid her intentions and waited til there was a gap in coverage. I don't think she was insane, I think she was evil. There is a big difference.