"Working long hours being single helps because your time is yours. Once you have a family your time isn't all yours anymore. Most of the Mac team, we were in our mid-20's, most of us were single, and we were able to essentially devote our lives to it"

In this quote, Andy Hertzfeld is highlighting the benefits of being single while working long hours. He discusses that when you are single, your time is totally yours to utilize as you please. Nevertheless, when you have a household, your time becomes divided and you are no longer able to dedicate all of it to your work. Hertzfeld then goes on to mention his experience dealing with the Mac group in his mid-20's, where most of the team members were also single. This permitted them to totally dedicate themselves to their work and pour all of their time and energy into it. In general, the quote stresses the benefits of being single in regards to having more control over your time and being able to totally devote to your work.