The Profiler is just one tool at our disposal. Sometimes, we may want to perform customized profiling and logging of our code. Maybe we're not confident that the Unity Profiler is giving us the right answer, maybe we consider its overhead cost too great, or maybe we just like having complete control of every single aspect of our application. Whatever our motivations, knowing some techniques to perform an independent analysis of our code is a useful skill to have. It's unlikely we'll only be working with Unity for the entirety of our game development careers, after all.
Profiling tools are generally very complex, so it's unlikely we would be able to generate a comparable solution on our own within a reasonable time frame. ...