I think those are just the hours that her clinic is open and probably do not represent at all the hours that she works. When there is a problem with one of her patients (or the patients she covers when her partners are not available) she needs to be available, 24 hours a day. Even for a private practice elective spine neurosurgeon, just like most doctors of any specialty, they are working more than 40 hours a week. If this neurosurgeon is busy enough to have 3 operating days per week, she gets plenty of complications and off hour phone calls, etc., that also need to be dealt with.
It is true that just doing a simple elective spine practice you will not have the same working hours as the skull base neurosurgeon that is clipping 100+ aneurysms per year, removing tumors that 5 other neurosurgeons have said they won't touch, and taking trauma call one night in three. But when pre-meds say they are "interested in neurosurgery" as the original poster states, they usually don't get that interest from the "exciting" work of the elective spine surgeon. And, unfortunately, to do a lot of the other work a neurosurgeon does, and especially to be competent at it, requires a lot of time. I would venture to guess that if you polled all the neurosurgeons in practice that do only elective spine, 90% or more would say that they weren't planning on doing this when they started on the long road of becoming trained in neurosurgery. Most people get interested in neurosurgery because of the rush of treating these patients with very complicated disease.
If you are interested in neurosurgery for elective spine and want a life, go for it...you can make your life pretty sweet. Just realize that the residency is usually the considered the most grueling (the residency programs are small so there are few residents, there are tons of patients demanding your time, patients can be very sick, and emergencies happen often). If you are interested in the cool cases (like aneuryms, tumors, functional/epilepsy, trauma...and you'll get plenty of that in any residency worth it's salt plus all the spine you could want) realize that you will be committing a lot of your life doing that (both in residency and in practice). Taking care of patients that have entrusted their lives in your competent skills (skills that don't come easy) requires some personal sacrifice.