The problem is it's hard to be creative or insightful if you are working that hard * , which means that you won't see the simpler way that saves a lot of time.

The problem is it's hard to be creative or insightful if you are working that hard * , which means that you won't see the simpler way that saves a lot of time. So you can do it, but only for mindless repetitive mechanical work, that doesn't require creativity - but then again, that's exactly the kind of work that is ripe for automating, though doing so usually takes some insight and creativity. This is not what you're talking about, but an exception is someone I knew who would code 30 hours straight, because it enabled him to keep all the code in mind, instead of having to reload it each day. I think it took a few days break after each such session. * irrelevant to the question, but if "programming" includes thinking about it in the back of your mind, while day dreaming, asleep, having a shower etc, then you can "program" 24/7.