Stuff like this doesn't make much sense if you're salaried. People like to break down salaries by the hour, but it's just not true. You can put in all the overtime you want and not see an extra penny of profit, at least not directly. You'll only benefit from it if you actually get a promotion or raise as a direct result of the extra work.

If you're contracting, though, and actually charge by the hour, then this calculation makes sense.

Also, this is tangential, but $200k is hardly an even remotely typical salary for a developer in the US.