Not miss a beat phrase
The `beat' referred to here is probably a heartbeat, although it may refer to a beat in music.
To not hesitate, be distracted, or show that you are not confident.
The teacher didn't miss a beat when the principal dropped in unexpectedly.
I really admire his concentration. He's never missed a beat, no matter how noisy the surrounding gets.
To carry out something without making any errors or experiencing any failures.
After writing, I check the essay once again to make sure that I didn't miss a beat.
I thought there had been some grammatical errors in the essay, but it turned out that I hadn't missed a beat.
This phrase dates from the mid 1900s.