While talking with my wife, I gained a big insight into the kind of work I like to do.
The greater this fraction, the more I will like the work:
The greater the importance (e.g., to the company, or to me), the more I like it. The quicker I can do it, the more I like it. But if the project isn't very important, I won't really like it. Or if it takes a lot of time, I won't like it.
This is why I really enjoyed building Yubnub (high importance to me, only 24 hours spent). Conversely, I hate debugging intermittent production issues (the bug isn't really important to the company, and it takes days or weeks to figure out).