Kill_Switch already explained the save systems, but Misanthropologis you got a fair point. The bugs definitely need ironing out and I'm working every day to get things into better shape. All of a sudden the game got a lot more players and that's why more and more never-before-heard bugs keep appearing too. I don't like the idea of constant save function though, because it would mess up the tension of the game.
To Ironoverload and Misanthropologist. There is a mod that gives you an unlimited save book, on the Discord server. It's also a rebalance patch, but you can install only the save-book part of it.