Luke 10:41-42
⁴¹ And Jesus answered and said to her, “Martha, Martha, you are worried and troubled about many things. ⁴² But one thing is needed, and Mary has chosen that good part, which will not be taken away from her.”

It's fairly common for Christians to thoughtlessly talk about "excellence in all things" as though this were something taught by the Bible and/or taken for granted in Christian life.

If anyone will actually stop and think about it, however, the idea is ridiculous even on a purely natural level:

1. Excellence in this life is unusual.  When we find a person who keeps an immaculately clean house, or a mechanic who does thorough, honest, and correct work, or even someone who actually uses correct spelling and punctuation in emails, we notice it, because it is out of the ordinary.
2. Excellence in this life is difficult.  We take it for granted that Olympic athletes make sacrifices to get to the top of their sport, or that those who want to go to top-tier medical schools will need to skip some parties in college.

The reality is that "excellence in all things" is impossible.  Life in the modern world - and I suspect life in this age in general - requires "triage."  Some things (for example, keeping your car or house clean, answering all your email, etc.) must intentionally be done with mediocrity if you want to do the things that really matter with excellence.

Someone might argue that on the basis of Mark 7:37, striving to do all things with excellence is required if we want to follow Jesus' example.  I reply that first, Jesus was not a sinner, and you and I are - we waste vast amounts of time and emotional energy in thinking about, committing, repenting of, and trying to make amends for sin, and Jesus did not.  Second, the crowd's statement about Jesus must be taken in context.  Did they mean that Jesus kept His house exceptionally clean?  I doubt it.

In fact, what we see in Jesus' life and teaching is a triage so radical that it makes us uncomfortable.  He lived a very simple life.  He repeatedly counseled people to stop worrying about clothes, possessions, health and reputation.  He went without sleep and sometimes without food in order to pray.  He was shockingly indifferent to His public image.  And on at least two occasions, He explicitly told people that there was only one thing that mattered in this life. (Matt 6:33, Luke 10:42)

So as for me, I want to agree with Jesus.  I want to do one thing with excellence, and let everything else be mediocre.  I want to excel at "sitting at Jesus' feet and listening to His word."  He said that the rest would fall into place if I put His kingdom first.  But even if some things don't work out well, from the perspective of eternity, it will be a good trade.