Cal Newport discusses the difference between controlled and pathological perfectionism:
The important part of my process — the part that separates this obsessiveness with the pathological variety — is that when my interval is done, I stop. Inevitably, I’m still well short of an ideal output, but what matters to me is not this specific outcome, but instead the striving for perfection and the deliberate practice this generates.
In other words, I want to keep getting better, not necessarily make this particular project the best thing ever.
Really, really good stuff.