And “save as” every few times (or every time if the document is important).
I lost a lot of work hours once because I was using a program that saved a backup copy every time you saved (so that you'd always be able to recover the previous version), and the damn thing crashed while saving, thus corrupting both the save file and the backup. Never. Again. Hard drive space is less expensive than my time and what's left of my mental health.
Exactly. I don't want my computer doing things without me telling it to. If I want it to save the file I will tell it to save the file. If I don't tell it to save the file, I most definitely don't want it to save it behind my back. Auto save is an anti-pattern, especially if it overwrites your manual save files.
(Saving an independent recovery file, preferably including undo and redo history, might come in handy in case of crashes, sure, but it should be optional and never on by default, out of privacy concerns; other users might use the computer, and it's safer to assume that the previous user might not want others to see the documents they had open last time.)