Generally, it is best to do a .SAV anytime you are about to do something that may have a major effect on the game. However, I am guilty of not following my own advice at times. In my current game on Play the World, with a modified Test of Time, I failed to do a ,SAv right after the Iroquois declared war on me, and again when I decided to hit the Songhai. The result was I think that I triggered one major Barbarian uprising too many while this was going on and the game crashed. The game was getting a bit flaky before that, so I was pushing the limits before the uprising. I can go back to the last .SAV prior to that however, and change what I am doing. My guess is that I still will end up at war with both civilizations, but there are some things that I can do to reduce the problems with the Barbarians. Hopefully, that will avoid the crashing. When I am doing a DEBUG game, I save fairly frequently, as those are tests, and I like to see the results of various actions.