> You can average it out at 30% of the time, but in a given week, you can't commit to it, because a greater responsibility of your job is being available to manage the unexpected

I'd argue that your job is to teach others how they can best manage the unexpected. Then you should only be involved in the really exceptional circumstances, allowing you more time to tend to your (metaphorical) garden at work. If writing code is part of that, so be it. But the bulk of time, I'd argue, ought to be in mentoring others.

The best managers I've worked with don't run around like chickens with their heads cut off, constantly responding to fires.