Should you create textbook ancillaries yourself?

Q: “Should you create ancillaries yourself?”

A: Michael Sullivan, author of 50-plus mathematics textbooks:

“In the first edition of your book and if you’re in an area where a solutions manual is typical, do it yourself. The pattern of a solutions manual must match the way they are done in the example. If this is not consistent, it will be confusing to the reader. In later editions, you can have someone else do it because you’ve created the model for how to do it.”