Part of the problem is it's not obvious why you need to do this until you need it, at which point it's too late. Reasons include: understanding how a change wo

Part of the problem is it's not obvious why you need to do this until you need it, at which point it's too late. Reasons include: understanding how a change works (all related code in one place without extra distraction), easy to revert, easy to figure out why that code is there during a blame.