Something I remember Steve Zegree reminding us of repeatedly in Gold Company:
Once you proven that you can sing a phrase properly – in tune, balanced, blended, dynamics, etc. – anything less than that is unacceptable.
Once you’ve cleared the bar, you have proven you can do it consistently well, and there’s really only one reason for not doing it well.
Focus.
It’s entirely mental. You are tired, unfocused, or just distracted, and don’t sing it as well as you can.
And that is a pretty poor excuse for taking steps backwards in your growth.
This is a strategy valuable in teaching, parenting, life: pair praise for a job well done with a reminder that that job must remain well done. Now that the bar is set, anything less is unacceptable.