Happens to me as well, and while it seems slightly more likely to occur after 1-2 hours of playing, it can happen anytime really. The mod that let's me quick save whenever I want has become absolutely crucial, but it's still extremely frustrating to crash this often. I find myself save-scumming like crazy, which is the opposite of what survival mode was supposed to be like. While this is the most common crash I experience, update 1.5 has made the game much more unstable in general and I get other random crashes as well. Before update 1.5 I had played well over 300 hours and only had 2 crashes, so they have definitely messed up with this recent update. Unfortunately Bethseda doesn't seem to acknowledge this yet, so I have no idea when we can expect a fix.