As for deadlines, I think more writers need to be up front with their publishers. The publisher asks, can you do it in six months. Can you? If you're not sure you better speak up. Nothing like locking yourself into a three book deal and not keeping up on your end. If you rush, will it be substandard? I've heard horror stories. When you sign that contract, you better be damn sure you can do it. If not, you're putting your career and name on the line. What can happen is you turn out a great first novel, the next one sucks and then not only are you out money and time, you're out readers who had faith in your work. The third ends up dropped by your publisher and you're lucky if they don't drop you.
Yes it's damn hard getting published, harder yet staying there. You have to be honest, with yourself and your publisher. I've waited a year for a book to come out and I survived the wait. Fans waited for Harry Potter, they wait for Jim Butcher, Karen Marie Moning. Writers can say "No, I need longer." Especially if the book you deliver lives up to expectations.
So are ya'll asking me to pity these successful authors because they don't know how to say "No, I need more time than you're suggesting?"
Beginning authors get crucified for less.