Lately I have been thinking about points of diminishing returns, and perfectionism.
The Pareto Principle or 80-20 Rule says -- among other things -- that roughly 80% of benefit is derived from 20% of the work. Another statement is, "the first 90% of a task takes 90% of the time, and the last 10% takes the other 90% of the time".
Now, for maximum productivity, one should always pull-up short when the first 80% or -- thereabouts -- is covered, and move on to other tasks. But in practice there will be times when you need to go that last 20%. For example, if you are competing on quality, that last 20% is going to be important at least some of the time.
I have my own principle, The Wedding Reception Principle, which is even more useful than the Pareto Principle. It states that in any broad endeavour, if all aspects are up to a good-standard then people will be struck by the excellence of one-or-two outstanding aspects. On the other hand, if any one thing is sub-standard, that is what people will remember, regardless of whether everything else is exceptionally good.
For example, at a wedding reception, if the food is bad, that will be what everyone talks about, not how great the speeches were or how much fun the dancing was. But if the food was merely ok, and the speeches outstanding, it will be the speeches that everyone remembers and talks about, and their general impression will be positive.
In other words: Make everything good, nothing bad, and a few things extraordinary. And pick those things that you intend to be extraordinary carefully, because you will be fighting Pareto and spending lots of time on them. It would be a shame if they turned out to be relatively unimportant.