Take this as a possible outcome to your writing endevours… You start your novel after months of thinking and research and you decide to subscribe to the school of thought that “Once you start, you just keep going! No matter what! Write you crazy person! Don’t you dare falter! Get that first draft out! Don’t stop until the end… then go back and edit.”
Been there done that, and editing under those conditions is a bitch.
So, how many false starts are OK? In my humble opinion? As many as you like.
There’s an inner editor we, as writers, all have (I’m going to direct you to “Let me Out! 49 Great Escapes from Writer’s Block” for more about it). It’s the voice in the back of our heads or the feeling in our gut that tells us something isn’t right. To ignore it and keep on going when you feel the overall plot is rubbish, just doesn’t make sense. So start over!
If you’re struggling to get past the first, second or third chapter, then stop, bin what you’ve written, review your characters, plot, the whole damn idea, and fix what needs to be fixed. Then start again.
If you have to do this a dozen times, that’s fine. Just don’t waste time finishing something you know isn’t right.
Happy writing, no matter how many times you start.