Only in failure do tests provide value.

“To my surprise, most of the team was quite motivated to improve things but they didn't really know how.”

This should not be controversial. It's effectively a tautology.

Three times unit tests saved me, in as many days.

Lack of unit testing drives the need for manual testing. Since testing is bunched up, development is as well.

Multi-stage software delivery means no hotfixes, or lots of extra work.

One of these skills, if you're good at it, diminishes the need for the other other.

I had failed to complete the "refactor" part of "red/green/refactor" several weeks ago, leaving me with some redundant tests that came back to bite me.

When copying a test, make your changes from the bottom up, renaming the copied function as the last step.

Who is responsible for unit, integration, and acceptance testing? Developers.

Test coverage for its own sake is dangerous. It leads to foolish technical choices.