Writing curriculum for a variety of organizations over the years has led me to adopt certain beliefs about the work. Here are some rules of thumb I use to create and edit my writing projects when the goal is engaging, useful, valid learning.

As wonderful as curriculum may look on the page, if anything is stated as a fact it must be fact checked before it goes public. The most credible author to fact check is neuroscience tried and tested by actual scientists. The trick is that common sense is often at odds with common science. Common science - although less popular in a sound-byte heavy world - is more respected by more intelligent people.
Just because a something makes sense doesn't mean it's true.
Just because something is dramatic doesn't mean it is true.
Personal boredom is not a valid reason to make changes to existing, working curriculum. Updating to meet new understanding is great. Reinventing curriculum that the public/client already loves and is proven successful is self centered. If people love something it should be carefully considered as to why. Success demands respect, not tweaking to suit personal design preferences without evidence of merit.
It is okay if the writer/teacher does not personally find value in a concept as long as he believes others can find value in it. But that being said, using and modeling concepts is a more integrated platform from which to teach.
New curriculum: Test it and let other trainers test it before making a final decision about whether to keep it.
Curriculum must be executable by the intended trainers, not just the author/teacher.
Curriculum should be based on the most memorable, relatable, and implementable version of a relevant topic for the audience.
Everyone's a critic, but creators are rare. Steve Martin once said of a bad review of one of his plays, "I wrote a play and he wrote a review, and that's the difference between us."