Pictures and video save to the card by default
Nothing to lose any sleep over, but one to be aware of nonetheless - you may run into a couple small pain points (or simply some waiting) by removing the SIM every time you remove the SD card.
Every time you remove and replace the SIM the phone will take a little bit to re-connect to the network and negotiate things, and in some cases that'll require a reboot of the phone if it's been a while. That means if you're going to want to use your phone for calls and data while the SD card is out, you'll have to replace the tray with just the SIM - and then, of course, remove the SIM once again to put the SD card back in the phone. Even though you're more likely to want to remove the SD card for data transfers to/from a computer than you will remove your SIM card, in this instance you don't have a choice - removing the SD card is also going to pop out your SIM. In an effort to simplify things, Samsung uses one slot in the body of the Galaxy S7 to hold a single tray with both the SD card and SIM card in it.
