My discovery of the day: Mac internet sharing works during software update.
I set up my macbook as a wi-fi hotspot and use internet sharing for big downloads to my phone. Today I applied software updates on the mac, and realized that my phone still had connectivity through the install until the final moment when the macbook restarted. That surprised me. I figured Apple would shut off all networking during the software update. Now I wish I had tried to ssh to the macbook during the update just to see if it would work.