[computereye]

They lie. Most candidates will tell you the coding exercise took less than it actually did because 1) they want to appear efficient 2) you said it would take only 3 hours so if they say it took 8 hours it would look like a failure

Source: me, last week, for another company. Plus, programming is not just writing code, most technical interviewers will want to see the global design, unit tests, comments, etc... Which are not accounted for in the expected time