That is probably close to true. The overall progression was extremely swift - five weeks from diagnosis to death - but as I recall that the 'final phase' was about 7 or 8 days after the decision to wrap things up (the timing is somewhat blurry in my recollection, because of how jarring it all was and also because I had to leave for a couple of days and go back). He was on very heavy morphine, fwiw, and it was probably the morphine that actually killed him in the end I suspect (though not officially, of course).
Yes, the morphine is what eventually killed my mother-in-law too. I was with her when she died a horrible death from cancer, she vomited blood at the end.