well, obviously taking less units per semester is forgivable when someone is working full or part time.
I'm planning on taking anywhere between 12-16 units a semester, NOT working, but doing some shadowing and volunteer work, maybe amount to about 10-12 her per week.
People I knew in undergrad that applied (and got into) medical, dental and pharmacy schools took the minimum # of units a semester, which at my university was 13 units, never worked crazy schedules and did the right amount of volunteer work. They were good. But maybe post-bacc is different and you have to work harder?
P.S Just out of curiosity, people who manage to work 40+ hours a week and still go to school full time, how do you do it? Do you work night shifts, or do the normal 9-5 and take all your classes in the evenings or on weekends? I tried to register for a few open university courses while working a 9-5, 40hr/a week job and found that these classes simply could not fit into my work schedule.