post a wall of shame for no shows. honor is worth way more than money, and more effective

Professors have been holding office hours for decades, and it is indeed a very efficient use of time if done properly.

The best part of it, if you're usually on the maker's schedule, is that you can set aside a period of time during which, and only during which, you're on manager's schedule. That's much better than switching in and out at irregular hours to attend meetings scattered all over the place. No show? Shame on you, but it's no big deal for me, because I wasn't planning to do anything terribly important during that time anyway. Maybe I'll check my email while I wait for the next appointment, and take care of, you know, managerial chores.

By comparison, if someone wants to see me in the middle of a 3-hour coding/writing/etc session, and then pulls a no show, the impact on my productivity could be a lot more serious.