Fay, there is Auto-Preserve that you can uncheck under Files > Preferences > General Program preferences > Auto-preserve. But there is also the Auto-Save that you can change (or remove) under Files > Preferences > Autosave Settings. There you can adjust the time between saves. Make sure you set it on the correct tab, which is the Edit workspace.
But as Ben mentions, it can save you some headache if your program or computer freezes or crash midway during a project. You can set it for every 20 minutes if you prefer. It also saves all the images on your workspace so if you have many images open.
