I'm confident enough to tout this number as effectively true, though I should mention that no company I work with has so far been willing to delete a whole day's work to prove or disprove this experiment yet.
Long ago when I was much more tolerant, I had a boss that would review all code changes every night and delete anything he didn't like. This same boss also believed that version control was overcomplicated and decided the company should standardize on remote access to a network drive at his house.The effect of this was that I'd occasionally come in the next morning to find that my previous day's work had been deleted. Before I eventually installed an illicit copy of SVN, I got very good at recreating the previous day's work. Rarely took more than an hour, including testing all the edge cases.