The most important aspect of an exercise program is consistency. This means that it is better to exercise whenever you have time as opposed to missing workouts (or not starting the program at all) because you won't be able to follow the optimum schedule. Hospitals could make it alot easier by having a workout room on site (that was free).
[edit: I used to be a trainer here:
www.protocolfitness.com]
If there are days that you can't get to the gym, you can always double up and do a split on your days off, such as doing cardio in the morning and weights in the evening.
Just don't give yourself a HA trying to follow the perfect schedule. It took me a long time to figure that out. Also, consistency is more important than being able to go 100% with every workout. It took me even longer to figure that out. Sometimes you have to have a light day. Just make sure it doesn't happen all the time.
I was thinking of starting a All Nurses - for - Life thread, but I don't think we can post our before pics. I'm getting married in 3 months and I would like to get my body fat percentage back down into the single digits, complete with my 8-pack, while attempting to conserve as much muscle as possible. Oh, and all while doing an accelerated BSN program.