I've discovered that I vastly underestimated the number of edits that a novel requires. After over twenty rounds of self-edits, some of which was based on feedback from beta readers, I was still hit by a ton of changes from my editor. Thanks, Sheryl!
The experience made me realize how important it is to have an editor go through your work. Beyond punctuation, sentence structure, spelling, word use, and other details, your editor will see things you've missed and and will identify gaps that need to be filled.
While beta readers are great, they aren't editors. They might catch a typo here or there, but in the end, they're reading for enjoyment. Your editor will come at the book with a critical eye, pointing out possible reader interpretations that may not have been your intent.
Yes, editing is the dreary part of writing. However, if you want your work to be polished and still make you proud years later, it's a very necessary process.
Thankfully, I'm done editing book one and have provided final submission to my publisher. However, book two is soon entering the editing process while I simultaneously work on book three and promote the sale of book one. My juggling act commences...