My dad would say similar things.
Boy, how wrong he was. (Fortunately, he was not pushy about it.)
In my years, I have learned the value of making mistakes, and not pursuing the path of minimal mistakes.
I have also learned the value of quitting. Always trying to be best in what I pursue would mean I would often pursue the wrong goals.
(Tangentially, "Finish what you start" ranks highly on my list of really bad advice).
I have also learned the value of "good enough". There are things I passionately want to be the best at. There are other things that have no value for me beyond being "good enough". Our dad's advice would ensure we either do not pursue the latter, or we aim for perfection in it to the expense of other endeavours.
Simply put, the advice is good only if you have unlimited time. When you get old enough and can reflect on your past, you'll get a better sense of how much time you have left and what you can accomplish in it. That time is very precious, and it may be in your best interest to be good at many things, as opposed to the best at a few (and poor at the rest).
I tend to agree. People have told me that they were only doing something because they started it and 'don't want to be a quitter'. My response is always that the concept of a 'quitter' doesn't really exist to anyone but high school football coaches.
In the words of Kenny Rogers, "You've got to know when to hold 'em, Know when to fold 'em, Know when to walk away, And know when to run…"
Which led me to not starting some things. I'm still learning when some things are "good enough". I still have the drive to do things "correctly". Which is a real pain when you need to speak a foreign language because you moved!
Interestingly, however, I kind of embraced the opposite of "finish what you start" - to the horror of my mother, I'm sure. I tend to work on bits of projects at a time, especially with hobbies. The downside is that occasionally I have a half-finished project that never gets finished. The more I learn to work with it, however, the more I tend to simply have projects (especially art) in various stages of finishing, but they all get finished. Overall, I find my finished projects are better for it.
This is a hard balance. I have found that being very close to the top in many different things you do while only being "the best" in one or two is far more productive and efficient.
Often the amount of effort you need to expend to be #1 instead of #2 is exponential. Sometimes it makes sense, but most of the time it doesn't.
And, if you are very consistently #2, you often wind up with the top spot more often than you would expect because #1 stumbles.
Consistency is consistently underrated. :)
Probably because it is not at all a balance.
I think this is an admirable heuristic in certain circumstances. It's important to note its perversions.
If you're measuring value by social ranking, you're incorporating others' values into your discovery process. This makes it difficult to do anything groundbreakingly unique. How can you be first if you're the only one racing?
(Then again, genius versus madness is a retrospective measure.)
(It's similar to Facebook's "Move fast and break things." It's a great phrase precisely because it's not the same generic advice everyone gives. There are times where it doesn't apply, that's more important than the times it does. Universal for all time advice sucks and is bland.)