1. You get distracted from your writing plan
The book is 90% finished so you lose motivation, having previously taken care to schedule your writing time. Writers are creative people, so they get distracted by new ideas; fresh information could affect how you want to end your book.
• Avoid writing two books in one – instead, give yourself the opportunity to expand your portfolio later. Jot down ideas for a second book and any follow-up research, then turn your mind back to the task in hand.