I have found carrying extra passport photos to be extremely useful while abroad, especially for expat-related activities like getting a local SIM card for my phone, acquiring visas, renting flats, registering with local offices, etc. Believe me, I’m less than thrilled about seeing my passport photos more than I have to, but it has tremendously helped me when I’ve needed to jump through bureaucratic channels quickly and get my work done. Instead of scouring a completely new city for places to get photos done, make it easier on yourself and just carry a few with you in your bag, so it’s ready to go on demand. Another use I can think of for extra passport photos is getting a new passport in case it gets lost or stolen. Thankfully, I haven’t had to deal with that, but if I ever did, I’d be thanking the high heavens for having my photos on hand. Also, store them in a plastic bag so they’re not exposed to any moisture or debris that inevitably falls into your bag while traveling. Another thing you can do is have a digital copy of your passport photos in your email and just print them as needed.