In some cases the final aspect of "fail" can be useful to prevent further investment in a dead-end. e.g. failing to make a perpetual motion machine. I would not

In some cases the final aspect of "fail" can be useful to prevent further investment in a dead-end. e.g. failing to make a perpetual motion machine. I would not use it to describe people but rather the specific solution/method being investigated. I think the most important thing is one's own mindset. I don't know how much 'fail' is in my vocabulary, but it's very hard to recall times when I completely ran out of options when working on a problem--usually I run out of time, start working on something more pressing, or the problem becomes less of a concern.