Almost everyday, often several times per day. Changes made more than 10 years ago help to fix bugs still present today even if the codebase has changed a lot (

Almost everyday, often several times per day. Changes made more than 10 years ago help to fix bugs still present today even if the codebase has changed a lot (they have commit messages, link to old tickets with more discussions ; sometimes, just the name of the committer tells a lot about what to expect from a change). I've spent a lot of efforts when we started migrating from SVN to git to not lose this, knowing the pain of not having the history go far enough (some of our projects were already migrated from CVS to SVN a long time ago, and histories where lost then). Efforts have been more human than technical, BTW, since not everyone was aware of the value of the history — usually bugs in the oldest parts of the codebase get through only a handful of people who have been there for a long time, and other people tend to take for granted that we understand why something is the way it is.