The final adjustment

The coach's comments were economical: she chose one change for me to practise rather than listing everything I had done badly. They were constructive, explaining what to try on the next stroke. I left the session with fewer notes than I had expected. That did not mean there had been less to learn. For once, I could remember the instruction while I was moving instead of stopping to consult a page.

From the passage, select two words or phrases that describe the style and usefulness of the coach's comments.