Many years ago, I worked at a company with a product that ran on Mac and Windows. The Mac version was pretty solid, but the Windows version had some problems.

They had a talented team of developers who were mostly Mac experts and just starting to get a grip on Windows.

I was known at the time as a "Windows expert", so they hired me to help the team get the Windows version into shape.

My typical day started with "house calls". People would ping me with their Windows questions and I'd go door to door to help solve them - and to make sure they understood how to do things on Windows.

In the afternoon, I would work on my own code, but I told everyone they could always call on me for help with a Windows problem, any time of day.

One colleague asked me: "Mike, how can you afford to be so generous with your time?"

Then in a performance review, I got this feedback:

"Mike, we're worried. Your productivity has been OK lately, but not great. And it's surprising, because the productivity of the rest of the team has improved a lot during this time."

I bit my tongue, but in retrospect I should have said:

"Isn't that what you hired me for?"