[unknown] For me I vary in my own rule when it's writing and chapter lengths. I assign each book of minimum capacity of words like:
Warning Dew Drop
Minimum: 1300
Maximum: 1700
Hannah:
Minimum: 1400
Maximum: 1900
Twelve Years Back
Minimum: 1350
Maximum: 1800
The Meeting Place
Minimum: 1500
Maximum: 2000