You can spend as much time on work as you want, but you only get so much time with your children. OP's point is that you should guard the time you have and spend it wisely. Personally, I find carrying a second device and keeping things separate part of maintaining a healthy balance between my work and my personal time.
I also don't want my personal devices or projects tied up in some corporate legal proceeding, so I keep them separate for that reason as well.