When I played clarinet in high school, I never practiced. I blamed it on my dog, who howled, but basically I was a lousy music student.
At my weekly lesson, though, the teacher would scold me, guessing that I'd only practiced three or four hours the week before. I was so good at sight reading that while I was truly mediocre at the clarinet, I was way better than anyone who had never practiced had any right to be.
We often test sight reading skills, particularly in job interviews. In that highly-charged encounter, we test the applicant's ability to think on her feet. That's a great idea if the job involves a lot of feet thinking, but otherwise, you're inspecting for the wrong thing, aren't you? Same with a first date. Marketing yourself to a new person often involves being charismatic, clever and quick–but most jobs and most relationships are about being consistent, persistent and brave, no?