For my first two children, no break-outs occurred. I am not sure why but they didn't make the attempt. For child no.3, there was been no individual break out but she has got out with conspirators.
First, the 7 year old, who has the strength of an ox, can actually lift her out. So we often find them downstairs of a weekend morning. But, this morning, the 7 year old was at a sleep over and the 5 year old, who has little strength, and our previously cot bound 2 year old, were downstairs.
So how did they do it? Well we have one of those cots where it requires someone to simultaneously press two buttons on either side of the cot and then using a finger or something, get the side of the cot down. A child doesn't have the wingspan to achieve this feat alone.
So what did he do? He explained to our two year old about pushing the little button on one side and whilst she did that, he pushed down the other and used his free hand to lower the side of the cot. They were free!