How do you use SOPs?

[Tom Harkins]

My day job involves launching and operating satellites, so SOPs are near and dear to my heart. We basically don’t go to the bathroom without a procedure.

I am still new to real estate investing as a landlord, currently self-managing 1 single-family rental. I have written 4 SOPs (making offers, listings & showings, tenant screening, and turnover). Most of their content comes from experienced investors' lessons learned shared here in the forums, and Brandon's book on managing rental properties. I've definitely pulled off the road during a podcast to jot down notes too.

So, how many SOPs do you use in your business? How often do you review and update them? What is an example of an event that caused you to?