I don't think number of features is meaningful, except if it's 0. Some features take a day, some take 2 months - I'd be 40x better if I only did the small ones :-)
Truth is, it's hard to evaluate coders. You need to at least be a decent programmer yourself. But even then there are many types of programming, and it's hard to measure effectiveness in large projects in a 1h interview, and people get stressed in interviews...