Effect: A witch can change her appearance for a number of hours per day equal to her class level, as if using disguise self. These hours do not need to be consecutive, but they must be spent in 1-hour increments.
What’s the time limitation for the witch’s disguise hex?
The hex’s description should say that the witch can use the ability for a number of hours per day equal to the witch’s class level. (This was added in the 2nd printing of the APG.)
Advanced Player’s Guide. Copyright 2010, Paizo Publishing, LLC; Author: Jason Bulmahn.