I still don't agree - my mum was diagnosed with cancer 4 years ago, she died 6 weeks later but it gave my kids the time to say goodbye and come to terms with it.
My father in law died of it 2 weeks ago. He was ill for a couple of weeks first, we visited on the Tuesday and he was frail but chatting to the kids. On the Wednesday he was taken into hospital and they found the cancer, come the Friday the decision had to be made to turn off the life support as both his liver and kidneys had failed. 9 hours before he passed he told us to tell the kids he loved them.
It was brutally fast but still gave the kids a brief amount of time to accept it was inevitable and gave both my wife and his wife a chance to say their final goodbyes.