I have talked about my ability to hear high pitched sounds before.
Recently I have worked out a source of this noise: automated lights.

The motion sensors on lights emit sound just outside the “normal human range”.
I had thought that it was fire alarms, but these are now more common.

The average time a developer spends at any given company is 2-3 years.
This seems to also apply to more senior positions such as CTO’s.

A new CTO will arrive, hopefully wait 6 months before starting the changes that they want to make to the organisation.
This puts an upper limit of 3 years on any change program.

The problem comes when you have systems that are 3-5 years old. That can mean that very few (if any) of the initial developers are still working at the company. Those that are will either be deeply embedded in systems or have been promoted to different areas.

This is where having living documentation and actively maintained tests come in handy.