My protocols for the office are basically check lists, sometimes with options and branching, describing how a task or set of tasks should be performed.

Originally, the office didn't have any, which was way too few, now, after looking at the list I posted a few days ago, I may be going too far the other way.

Still, I find having protocols useful in several ways:

Codifying how a given process is successfully completed gives a better understanding of what the process is trying to achieve, where it works well, where it has frictions points, and where it doesn't work at all. The process also helps highlight edge cases, decreasing the likelihood we'll be caught off guard.
Giving my employees a clear understanding of their job responsibilities and how they'll best achieve them. Protocols are always updatable, and if they have better ideas, or identify problems we improve them.
Clear goals, expectations, and processes mean increased efficiency, easier collaboration, and generally reduced stress for everyone involved.
A double edged promise: If you follow the protocols I've approved and something doesn't work, that's on me, and I'll take full responsibility. However if you don't follow them and you make a mistake you otherwise wouldn't have, that's all on you.

This is why it confuses the heck out of me when employees ignore the protocols, make overt mistakes, and are then confused why they're in trouble. We've been doing this for almost 15 years, and it feels like everything we've learned we've learned the hardest way possible. All that learning has gone into the protocols our current employees are asked to work from, and when they ignore them to make the same painful mistakes we've worked so hard to solve, and worse make a habit of those mistakes, it's deeply aggravating.

So the final use of protocols: Firing people with cause.