People laughed at me when I said that I was carrying around a dozen spare passport photos, but they’ve been incredibly useful and saved me a ton of time and hassle.
Who wants to wander the streets of some rural town in Cambodia searching for someone who can take your photo? Friends of mine had to do this!
I’ve used them to apply for visas around the world, to get a new passport when mine expired while I was on the other side of the planet, and I even needed one to buy a local SIM card in Nepal! Having spares in my backpack meant that I didn’t have to waste a day researching and then wandering around a city to try to find someone who could take a passport-sized photo of me.