There's a long article in the New Yorker by Atul Gawande, who wrote the Checklist Manifesto. In it, he describes the research he did about the kinds of professions which have coaches, and those who don't. Professional musicians, for example, don't tend to have coaches. Surgeons, Gawande discovered in practice, do not. Athletes do.
The article suggests that it's not that musicians and surgeons can't learn from coaches, just that it's not 'done'. Athletes have coaches - we expect them to. Gawande decided that he would find a coach, not worry about what anyone else thought and see if it helped. His coach found hundreds of small things he could improve, and he has kept the habit.
Mark has said previously, 'everything decays'. Even if you are currently perfect, your performance will decay over time. We become lazy. We take short cuts. We learn bad habits and continue to fall into them. Admitting this, and asking for outside eyes to help you to keep optimum performance, and even surpass it, is commitment to the people you serve, whether they are hospital patients or printer purchasers.