What would safe mode do or would I always need to start it in safe mode?
Safe Mode temporarily disables all 3rd party apps you installed. It helps to narrow down an issue to something you installed vs the system or hardware. If the problem goes away in Safe Mode, then the problem is being caused by something you installed, but then you'd have to uninstall apps one by one until the problem goes away.
The Oreo update for the S7 seems to be pretty glitchy, based on numerous posts here and other articles I've read. If that's the case, then all you can hope for is that Samsung pushes some patches.:-\