You are correct that box is a place to start.
Originally Posted by Jaf-Photo
The films and developers are not the wildcards, we are, all us nuts behind the cameras and agitating our films.
The materials we use are remarkably reliable and consistent as long as we do our part.
Our vision for the end result and our preferences in how we like to do things are what drives us to deviate from "normal". These decisions are regularly poorly informed and done for irrational reasons.
As to color forcing us to stay close to box speed, that is at best an urban legend. Kodak's old Portra brochures claimed consistent color from one stop under to two stops over. Disposable cameras are more proof of that.