Software development topics I've changed my mind on

> Good management is invaluable. (I went most of my career before seeing it done well)

Yes, and: it's difficult to describe, must be led from the top, and extremely difficult to evaluate from above.

If the person at the top can come down for a coffee with people who endured some bad management, and ask honest, non-loaded three questions, it can be measured qualitatively but with very high accuracy.

The three questions are:

    - What should we start doing?
    - What should we continue doing?
    - What should we stop doing?

This is an immensely powerful tool. Thanks to the awesome person who introduced me this.

Addenda: "Theory X" is something really bad. If you're working with a team which responds positively to Theory X, you have much bigger problems IMHO.