I think 10:1 is a good rule of thumb, but it does feel like time is a function that needs to be accounted for, too. It would also be interesting to think throu

I think 10:1 is a good rule of thumb, but it does feel like time is a function that needs to be accounted for, too. It would also be interesting to think through how many changes there are _between releases_ of a project. MySQL is 23 years old [1], but what's the effort/change between major releases at this point? That's where the rule sort of falls down for me: a book has a few editions (if it's lucky); software, on the other hand, has lots of releases if it's successful. [1] Crap, now I just feel old, too...