Is there a word or a phrase for this phenomenon? When something becomes a habit requiring no thought at all and then, when forced to actually think about it, the brain draws a complete blank?
“A centipede was happy – quite!
Until a toad in fun
Said, "Pray, which leg moves after which?"
This raised her doubts to such a pitch,
She fell exhausted in the ditch
Not knowing how to run.“
From 1994!
And I like being reminded of the great pressure many creative spirits feel. It's serious business, managing pressure and also doing your work.
For the future, you can usually create these for yourself by going to top of the sites that I linked.