CBR is a complete joke. I keep seeing their articles pop up on my news feed in my phone in my browser and non of them have any value.
Like the MILLION articles that are titled "5 characters [blank] would win against & 5 they wouldn't". I can't remember a specific one but some involved really...
Overall how many buffer chapters you want is entirely up to you. I think rather than planning "How many" as a hard rule it's better to think about why you want them and how you plan to use them.
For example
Do you have school. work, or anything that can pick up or slow down resulting in your...