Unless its directly in your own interests, it's actually irrational to be working out of hours. If you're being paid for the extra work or you're the company owner or a major shareholder then it does make sense, but otherwise there's little benefit to be had. There might be other special circumstances, such as if you're working for a charitable cause where part of the benefit is in trying to improve the wider society, but in most for profit businesses this doesn't apply.