I am currently in my third and final year of my PMHNP program. I have maintained full-time employment (along with PRN employment at my other job) thus far. I am currently in my first practicum course, and it has been feasible so far. However, it is a summer course, and I only need 90 hours. Next semester, however, I am going to have to get in 270 hours of practicum, and I have had to find several co-workers to swap shifts with me so that I can do practicum 3 days a week and still work my 3-12 hour shifts. I have to stay full-time to keep my employer's tuition discount. I also assume that I will not be able to work my PRN job once the fall semester starts as well.
In short, we do what we have to do. I have to maintain full-time employment to keep my tuition discount, pay my bills, and support my family. It certainly isn't ideal, and it is exhausting, but we do what we have to do to get by. If you don't "have" to work full-time, it is probably best for your grades and your mental health to no work full-time. But it is certainly not impossible.
Hope this helps!!