Why does nobody mention that a book has 11 spine points, not one

I was reading through a 1998 copy of Bookbinding and Conservation by Bernard Middleton that a retiring binder in Rochester sold me for $30, and he points out the spine actually has 11 flex points you have to plan for, not just the one hinge everyone worries about. I had been folding and gluing the same way for 14 years and never once counted them. Went back to my bench and checked a book I did in 2009, and sure enough the wear was all speckled along those spots instead of one clean break. It made me rethink how I score my boards before casing in, even on simple quarter binds. Does anyone here actually plan around all those points, or am I the only one who missed this?