Edit: the windows 3.1 manual "recommends" exiting windows before turning off the PC. It doesn't say it's "required". And with 386 mode, windows actually did do

Edit: the windows 3.1 manual "recommends" exiting windows before turning off the PC. It doesn't say it's "required". And with 386 mode, windows actually did do disk IO, including caching. Probably a lot of people did exit windows 3.x before powering off the computer. I actually don't think it was required. Windows 3.x was just a shell on top of DOS and didn't do any IO caching. Saving files or closing all applications should've been safe enough.