Is flexibility the same as unpredictability?

Thought on the anti-fair use meme being used, mostly, to oppose the introduction of fair use in other countries: the criticism is that fair use’s flexibility means that it’s inherently and undesirably unpredictable. (See, e.g., the Kernochan Center’s submission to the Australian copyright inquiry.) But those aren’t synonyms. My elbow is flexible, not unpredictable. Only if the overall system is in trouble is flexibility also unpredictability. As numerous scholars such as Pam Samuelson, Mike Madison, and Matt Sag have shown, there are strong patterns in fair use cases on which reasonable people can rely.