How Do You Know How Many Loops You Need?

How do you know how many Loops you need?

The first method: as many holes as you need for binding, you need as many loops
The second method: count the number of loop you need for double coils
The third method: know the length of your book, know the tooth pitch you need, divide the length by the fixed tooth length, and add 1-2 loops, which is the number of loop  you need.