A bit of space between you and your work is good at times. You come back at it with fresh eyes. Problems which once seemed insurmountable sometimes appear puny and easily dealt with. If the story’s working you’ll soon find your way back into it and begin to hit the kind of output levels you had before you took a breather.
The problem with the ‘I will write 40,000 words a month’ school of fiction is it’s based around quantity alone. What if half those words are the wrong ones? Then you’ve only written 20,000 words really. And worse, you’re going to have to spend time going through that 40K mess working out which ones are good ones and which ones expendable.
Writing’s not a race. At least if it is, it’s a marathon, not a sprint, for most of us anyway. How do I meet those deadlines? Simple, I take what’s in the contract and subtract a month or two of my own. Then carry on to my own schedule, not the contracts.
Books get finished through steady, efficient workmanship, produced by writers in control of their craft. Not by hammering out words incessantly and hoping that somehow in the end they’ll fit.