Book editing is like surgery sometimes, and your beta readers are your best doctors and nurses, and yet the final surgery depends on you!
Just when you think the last bug has gone extinct, you find something else. Or you know something is wrong, or your doctors tell you something is wrong, but you're in denial (doctors are the worst patients - writers are the worst crittees), until the symptoms keep showing up, and you know something must be done. Or else the warts or bugs or tumors will always be there eating away everything.
But let's face it, surgeries are painful. It takes time to heal, and often there are complications or new problems, and more fixes need to be applied. And you wonder if you'd come out alive or whole again. Would you be a better person? Or would you be a patchwork like Frankenstein's monster?
Fortunately, the best surgeons usually do the job well. That's when we, as writers, must sharpen our skills and improve our craft. The point isn't to write something perfect from the get go. the point is that when problem arises, we'd know and understand the need to do necessary surgeries, to fix any warts and bugs and tumors and ailments. Like everything else, the first step is to acknowledge that there is a problem - an illness, a cancerous growth... I think for us, that's the hardest thing, to listen to your doctor and realize: OMG, I have cancer, and I need to have X and Y cut out... But once you take the first step to acknowledge that, the rest would come naturally: you know what you must do if you want to live.
Writing is kind of like that, too. And right now, I'm doing surgeries, some minor, and some not so. They can be painful. But they are all necessary, and I'm glad I have the opportunity before the book goes to die.