I'm in the late stages of what will probably be the last substantial draft of BLUE REMEMBERED EARTH, mindful that while there will still be chances to make some minor changes further down the line, this is really the last opportunity to inflict major adjustments on the story. Along with detailed editorial feedback, I've also been fortunate enough to have responses from some "beta-test" readers who were generous enough with their time to take a look at the May draft. As always, emotions are mixed - these readers will inevitably pick up on plot holes and inconsistencies that you'd either thought were resolved or were not aware of at all, but at the same time it's encouraging to see that someone else is able to track through the plot from A to B to C and pick up on nuances that make it clear that they understood not only the surface currents of the story, but the implied mechanics of the invented world and its characters. That, in other words, they weren't completely bewildered and lost by chapter three. The hard part is sifting through those reader responses and deciding which you act on, and which you discard. Assuming, of course, that you can reconcile two or more sets of reactions which may not readily dovetail.
A book at this stage is essentially a done deal - a production slot is assigned, artwork commissioned, buyers (hopefully) persuaded of its worth. If a reader tells you that the motivation of character X in chapter Y needs a bit of tweaking, you can deal with that. If that same reader suggests that the entire premise of the novel is flawed, that the only possible course of action is a total rewrite or even abandonment, you have no real option but to discard their advice. That's never happened to me yet, but it's always a possibility. Writers are artists, but publishing is a commercial enterprise with schedules and expectations. The momentum may not be as unstoppable as that which governs the shooting and cutting of blockbuster films, assigned a tentpole release date a summer or two ahead which absolutely must be met, at all costs. But it's still momentum, all the same.