2 clients a day isn't part-time. Bored? There is more to life than working continually. Have a social life, continued education, hobbies, have a life. Then when you do work, you are working as a well rounded person and fulfilled in every way. For me that IS balance.
The wonderful thing about people is that we are all different and we all function and feel fulfilled in different ways. Seeing 2 or 3 clients a day works beautifully for me and in reverse, I personally wouldn't be happy if my whole working time was just work.
There is no right or wrong, just difference. I don't class myself as part-time though. I work every day if it suits me, if it doesn't... I don't!