Ctrl + S will be your best friend. Every 5 or 10 minutes, save your file.
After a few of disastrous misadventures this totally became my habit too :) But on the side note - there are a lot of solutions for autosaving in AI.
Like for example Astute's Autosaviour plugin (it's free) -
https://astutegraphics.com/software/autosaviourfree/