"Everyone in the company sees [your] plaudits and can pile on more unicorns if they agree that [you] did an awesome job."
The only person who will be impressed by you helping Bob upload to SharePoint is Bob. Total score: 1-3 unicorns.
Every engineer will be impressed that you fixed the thread dispatcher. Total score: 1-3 unicorns * # of engineers.
I've worked Unicorn in to my daily workflow. I can't say everyone (or even anyone) else uses my system, but Unicorn is my first stop of the day when I sit down at my desk. I look over all the unicorns from the previous day, distribute points as I see fit, and move on with my day. Rinse and repeat daily.
It takes all of ~2-3 minutes out of my day. I can see how this technique wouldn't scale well once employee numbers get too big, but it seems to work well at ~100 employees.