Sigh, I was afraid someone would take me perfectly literally. I did not mean that every waking moment should be devoted to building a killer application. I meant that she should try to be choosy about her precious volunteering and working time. It should be double- and triple-dipping, getting paid and getting vet/animal hours at the same time. There are only so many hours in the day, and if she wants to have fun and also get into vet school and also make money, she's gonna have to kill a few birds with one stone.
So, I actually disagree with this because I think it tends to decrease your diversity as an applicant. I worked two part-time jobs during undergrad and a full-time job after I graduated (I am a non-trad student), and none of these were animal-related. I also had to get my animal experience and veterinary experience, so you're right that it took a bit more time (I have fewer experience hours than many applicants, but my experience is very diverse).
When I interviewed (at UF and Ohio), both schools asked me questions about what made me a diverse applicant/differentiated me from the typical DVM candidate, and I was able to talk about my work experience. They also asked me how that work experience prepared me to succeed in veterinary school and as a veterinarian. My interviewers for both schools made it very clear that they agreed that my experience strengthened my application.
I'm not saying any non-vet experience will help, but if you can't find your dream clinic job, it's totally okay to look for something else. I am sure that you will acquire skills that will be applicable in the field - just know how to spin it. And if you do this, try to go for something else that you love - you'll be happier, and further down the line, it will demonstrate that you are an applicant with diverse interests who knows that you have other options, but still is choosing to become a veterinarian.
Someone else recommended getting a student job through your undergrad institution, and I highly recommend this. My two undergrad part-time jobs (one working in theater and one as a teaching assistant for an unrelated field) were through federal work/study programs, and I think it's a lot more flexible - they are understanding if you need to take some time off for finals or if you begin struggling in school. Also, they usually follow the college's schedule, which allows you to leave work for awesome animal/veterinary internships during breaks and still have your job waiting for you when you return.
Sorry for the megapost...
tl;dr - If you can find a job for animal/veterinary experience, great. If not, do what you need to do - you'll still gain skills and diversity. Work/study jobs may be more flexible if you're worried about academic performance.