That’s insane.
That’s insane.
It gets really complicated very quickly, but if you are single, have less income, and it's only from wages, it's much simpler.
As to the permutations aspect, this does take a lot of time but it can net a lot of savings. One thing that I would add is that you do have the choice to round to the cent or the whole dollar (at least with the IRS), but generally I have never found that to make any substantial difference, so I just round to whole dollars at this point and don't waste my time trying to optimize that.
You may find it insane, but I'm OK with it. I'm not going to knock somebody for doing something different, but I do think it is important to know how to do it yourself when push comes to shove.