temporary coverage hacks you wish you'd known sooner

Last weekend, my brother asked me to help him move his stuff across town. No biggie, right? Except he wanted me to drive the rental truck because he's terrible with big vehicles (his words, not mine, lol). Anyway, I realized my regular car insurance didn't cover rentals, and the rental company's insurance was kinda pricey for just a single day. Did some quick googling and found out you can actually get temporary insurance coverage for just a day or two - way cheaper and easier than I thought.

Ended up saving a decent chunk of cash, and now I'm wondering what other situations people have run into where temporary insurance saved the day. Like borrowing a friend's car for a road trip or test-driving a used car from Craigslist or something. I'm sure there's gotta be other clever uses I haven't thought of yet.