>> I tend to work myself out of a job.
>
>I'd take that as a sign you're doing your job right...

I agree. Just this past weekend I was helping my dad at his welding shop. He mentioned a welder they hired to do a particular job. They estimated it should've taken 6-8 hours. The individual did it in 18 hours. He's never been hired back, and won't be hired back. The people there believed he was padding the time to make more money than he should've for the workload.

It's always best to do your best and let the chips fall where they may. There are also times you can't work at your peak efficiency for whatever reason. Don't feel too bad about those times either, provided you're not purposefully goofing off.