I got my ARCs a week ago so I'm reading Macbeth's Niece one more time. My husband is surprised by the number of times it's been read, by me, by amateur helpers, by agents, editors, and who knows who else. (The worst part is that we're still finding things to fix!)
I've had people contact me and say, "I just finished writing a book and I'd like you to take a look at it." I always disappoint them by telling them to put it in a drawer for six months and then read it again. Nobody wants to wait when the next bestseller is sitting right there on their computer or desktop. Let's get it sold so everyone in the US can buy a copy!
Reading, rereading, and rereading again is a HUGE part of writing. They say Mozart formed his masterpieces in his head and simply wrote them down, but most of us can't do that. Each time I read my work I see something else that needs work: sometimes it's slips in voice, sometimes it's a tendency to go too long with a character thinking rather than doing. Whatever it is has to be fixed before the project is submitted, because the first professional who looks at it is going to be a lot more critical than your mom, your sister, or even that person in your critique group who wishes she could write as well as you do.
Does it get easier? I suppose it does, but if you read big names who crank out a book a year, you can often see evidence that more time should have been spent on editing. And no one edits your work as well as you, the creator, can when you are focused on the task.
How many times is enough? Just since my book was selected for publication I've read it five times, each time with a different editor reading between times. I can't tell you how many times I read it before that.
The point? When you tell the world that you're a writer, good for you. Just be sure you know that at least until you're famous enough to hire it done, the writer is the primary reader as well.