I'm student as of now, but I don't think I would mind taking some work home with me, I love to do outside research anyway. My expectation is to take some work home with me during my first job, I've always done that anyway, until I felt more comfortable with the job in general.
The best rule of thumb (I'm conjecturing) is still take time to relax, make dinner, take care of what needs taken care of at home, etc, before doing an hour or two of extra work outside of work hours. It's important to take time for yourself and still have a life outside of work (I'm assuming that's part of what you're looking for).
There's an excellent book for new practitioners to the "helping field," it's called the Resilient Practitioner, I believe. It talks about taking care of yourself and doing whatever IT is to maintain balance in your life. Don't know if it will help, but hope you find the answer you're looking for in any case!