I have worked with many people who do the same as well. You can do it if you're in a privileged job, like many of us work, or if you were hired under those circumstances. If you have a below-median wage job where you're expected to work 40hrs/week and you have a medical hardship, you'll be looking at being reassigned to a part-time position at best, and if one is not available, you'll be spending your FMLA time looking for a new job.