I had this exact conversation with a girl one time. She was the standard "work and work and work and work and work and you'll do well" kind of person, and I was more like you.

We were both in the lab, and she was working on finishing her assignment up for our class later in the day. I was reading Reddit and working on a side project at the time, and she asked how my assignment went. I replied that I wasn't yet finished, and she seemed horrified. I told her I had only about half an hour's worth of work yet, and I just simply didn't feel like doing it. My project was more interesting. She asked why I didn't just finish it and then I could "screw around" with the remainder of the time, because then I'd know I was done, and I couldn't really give her a better answer.

I started twenty minutes before it was due, and finished the work in ten.